Track Common Adversary Tasks Performed Using AppleJeus

Adversaries may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this case, the malicious emails contain links. Generally, the links will be accompanied by social engineering text and require the user to actively click or copy and paste a URL into a browser, leveraging User Execution. The visited website may compromise the web browser using an exploit, or the user will be prompted to download applications, documents, zip files, or even executables depending on the pretext for the email in the first place. Adversaries may also include links that are intended to interact directly with an email reader, including embedded images intended to exploit the end system directly or verify the receipt of an email (i.e. web bugs/web beacons).

Adversaries may also utilize links to perform consent phishing, typically with OAuth 2.0 request URLs that when accepted by the user provide permissions/access for malicious applications, allowing adversaries to Steal Application Access Tokens. These stolen access tokens allow the adversary to perform various actions on behalf of the user via API calls.

Audit

Audit applications and their permissions to ensure access to data and resources are limited based upon necessity and principle of least privilege.

Restrict Web-Based Content

Determine if certain websites that can be used for spearphishing are necessary for business operations and consider blocking access if activity cannot be monitored well or if it poses a significant risk.

Software Configuration

Use anti-spoofing and email authentication mechanisms to filter messages based on validity checks of the sender domain (using SPF) and integrity of messages (using DKIM). Enabling these mechanisms within an organization (through policies such as DMARC) may enable recipients (intra-org and cross domain) to perform similar message filtering and validation.

User Account Management

Azure AD Administrators apply limitations upon the ability for users to grant consent to unfamiliar or unverified third-party applications.

User Training

Users can be trained to identify social engineering techniques and spearphishing emails with malicious links which includes phishing for consent with OAuth 2.0

Monitoring the following activities in your Organization can help you detect this technique.

Application Log: Application Log Content

Logging, messaging, and other artifacts provided by third-party services (ex: metrics, errors, and/or alerts from mail/web applications)

Monitor for third-party application logging, messaging, and/or other artifacts that may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Filtering based on DKIM+SPF or header analysis can help detect when the email sender is spoofed. URL inspection within email (including expanding shortened links) can help detect links leading to known malicious sites. Detonation chambers can be used to detect these links and either automatically go to these sites to determine if they're potentially malicious, or wait and capture the content if a user visits the link.

Network Traffic: Network Traffic Content

Logged network traffic data showing both protocol header and body values (ex: PCAP)

Monitor and analyze SSL/TLS traffic patterns and packet inspection associated to protocol(s) that do not follow the expected protocol standards and traffic flows (e.g extraneous packets that do not belong to established flows, gratuitous or anomalous traffic patterns, anomalous syntax, or structure). Consider correlation with process monitoring and command line to detect anomalous processes execution and command line arguments associated to traffic patterns (e.g. monitor anomalies in use of files that do not normally initiate connections for respective protocol(s)).

Network Traffic: Network Traffic Flow

Summarized network packet data, with metrics, such as protocol headers and volume (ex: Netflow or Zeek http.log)

Monitor network data for uncommon data flows. Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.

Adversaries may abuse Unix shell commands and scripts for execution. Unix shells are the primary command prompt on Linux and macOS systems, though many variations of the Unix shell exist (e.g. sh, bash, zsh, etc.) depending on the specific OS or distribution. Unix shells can control every aspect of a system, with certain commands requiring elevated privileges.

Unix shells also support scripts that enable sequential execution of commands as well as other typical programming operations such as conditionals and loops. Common uses of shell scripts include long or repetitive tasks, or the need to run the same set of commands on multiple systems.

Adversaries may abuse Unix shells to execute various commands or payloads. Interactive shells may be accessed through command and control channels or during lateral movement such as with SSH. Adversaries may also leverage shell scripts to deliver and execute multiple commands on victims or as part of payloads used for persistence.

Execution Prevention

Use application control where appropriate.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments that may abuse Unix shell commands and scripts for execution. Unix shell usage may be common on administrator, developer, or power user systems, depending on job function. If scripting is restricted for normal users, then any attempt to enable scripts running on a system would be considered suspicious. If scripts are not commonly used on a system, but enabled, scripts running out of cycle from patching or other administrator functions are suspicious. Scripts should be captured from the file system when possible to determine their actions and intent.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor for newly executed processes that may abuse Unix shell commands and scripts for execution.

An adversary may rely upon a user opening a malicious file in order to gain execution. Users may be subjected to social engineering to get them to open a file that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Attachment. Adversaries may use several types of files that require a user to execute them, including .doc, .pdf, .xls, .rtf, .scr, .exe, .lnk, .pif, and .cpl.

Adversaries may employ various forms of Masquerading and Obfuscated Files or Information to increase the likelihood that a user will open and successfully execute a malicious file. These methods may include using a familiar naming convention and/or password protecting the file and supplying instructions to a user on how to open it.

While Malicious File frequently occurs shortly after Initial Access it may occur at other phases of an intrusion, such as when an adversary places a file in a shared directory or on a user's desktop hoping that a user will click on it. This activity may also be seen shortly after Internal Spearphishing.

Behavior Prevention on Endpoint

On Windows 10, various Attack Surface Reduction (ASR) rules can be enabled to prevent the execution of potentially malicious executable files (such as those that have been downloaded and executed by Office applications/scripting interpreters/email clients or that do not meet specific prevalence, age, or trusted list criteria). Note: cloud-delivered protection must be enabled for certain rules. 

Execution Prevention

Application control may be able to prevent the running of executables masquerading as other files.

User Training

Use user training as a way to bring awareness to common phishing and spearphishing techniques and how to raise suspicion for potentially malicious events.

Monitoring the following activities in your Organization can help you detect this technique.

File: File Creation

Initial construction of a new file (ex: Sysmon EID 11)

Monitor for newly constructed files that are downloaded and executed on the user's computer. Endpoint sensing or network sensing can potentially detect malicious events once the file is opened (such as a Microsoft Word document or PDF reaching out to the internet or spawning powershell.exe).

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor for newly constructed processes and/or command-lines for applications that may be used by an adversary to gain initial access that require user interaction. This includes compression applications, such as those for zip files, that can be used to Deobfuscate/Decode Files or Information in payloads.

Adversaries may abuse the Windows Task Scheduler to perform task scheduling for initial or recurring execution of malicious code. There are multiple ways to access the Task Scheduler in Windows. The schtasks utility can be run directly on the command line, or the Task Scheduler can be opened through the GUI within the Administrator Tools section of the Control Panel. In some cases, adversaries have used a .NET wrapper for the Windows Task Scheduler, and alternatively, adversaries have used the Windows netapi32 library to create a scheduled task.

The deprecated at utility could also be abused by adversaries (ex: At), though at.exe can not access tasks created with schtasks or the Control Panel.

An adversary may use Windows Task Scheduler to execute programs at system startup or on a scheduled basis for persistence. The Windows Task Scheduler can also be abused to conduct remote Execution as part of Lateral Movement and/or to run a process under the context of a specified account (such as SYSTEM). Similar to System Binary Proxy Execution, adversaries have also abused the Windows Task Scheduler to potentially mask one-time execution under signed/trusted system processes.

Audit

Toolkits like the PowerSploit framework contain PowerUp modules that can be used to explore systems for permission weaknesses in scheduled tasks that could be used to escalate privileges. 

Operating System Configuration

Configure settings for scheduled tasks to force tasks to run under the context of the authenticated account instead of allowing them to run as SYSTEM. The associated Registry key is located at HKLM\SYSTEM\CurrentControlSet\Control\Lsa\SubmitControl. The setting can be configured through GPO: Computer Configuration > [Policies] > Windows Settings > Security Settings > Local Policies > Security Options: Domain Controller: Allow server operators to schedule tasks, set to disabled. 

Privileged Account Management

Configure the Increase Scheduling Priority option to only allow the Administrators group the rights to schedule a priority process. This can be configured through GPO: Computer Configuration > [Policies] > Windows Settings > Security Settings > Local Policies > User Rights Assignment: Increase scheduling priority. 

User Account Management

Limit privileges of user accounts and remediate Privilege Escalation vectors so only authorized administrators can create scheduled tasks on remote systems.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments for actions that could be taken to gather tasks may also be created through Windows system management tools such as Windows Management Instrumentation and PowerShell, so additional logging may need to be configured to gather the appropriate data.

File: File Modification

Changes made to a file, or its access permissions and attributes, typically to alter the contents of the targeted file (ex: Windows EID 4670 or Sysmon EID 2)

Monitor Windows Task Scheduler stores in %systemroot%\System32\Tasks for change entries related to scheduled tasks that do not correlate with known software, patch cycles, etc.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor for newly constructed processes and/or command-lines that execute from the svchost.exe in Windows 10 and the Windows Task Scheduler taskeng.exe for older versions of Windows.  If scheduled tasks are not used for persistence, then the adversary is likely to remove the task when the action is complete.

Scheduled Job: Scheduled Job Creation

Initial construction of a new scheduled job (ex: Windows EID 4698 or /var/log cron logs)

Monitor for newly constructed scheduled jobs by enabling the "Microsoft-Windows-TaskScheduler/Operational" setting within the event logging service.  Several events will then be logged on scheduled task activity, including: Event ID 106 on Windows 7, Server 2008 R2 - Scheduled task registered; Event ID 4698 on Windows 10, Server 2016 - Scheduled task created;Event ID 4700 on Windows 10, Server 2016 - Scheduled task enabled;Event ID 4701 on Windows 10, Server 2016 - Scheduled task disabled

Adversaries may create or modify Launch Daemons to execute malicious payloads as part of persistence. Launch Daemons are plist files used to interact with Launchd, the service management framework used by macOS. Launch Daemons require elevated privileges to install, are executed for every user on a system prior to login, and run in the background without the need for user interaction. During the macOS initialization startup, the launchd process loads the parameters for launch-on-demand system-level daemons from plist files found in /System/Library/LaunchDaemons/ and /Library/LaunchDaemons/. Required Launch Daemons parameters include a Label to identify the task, Program to provide a path to the executable, and RunAtLoad to specify when the task is run. Launch Daemons are often used to provide access to shared resources, updates to software, or conduct automation tasks.

Adversaries may install a Launch Daemon configured to execute at startup by using the RunAtLoad parameter set to true and the Program parameter set to the malicious executable path. The daemon name may be disguised by using a name from a related operating system or benign software (i.e. Masquerading). When the Launch Daemon is executed, the program inherits administrative permissions.

Additionally, system configuration changes (such as the installation of third party package managing software) may cause folders such as usr/local/bin to become globally writeable. So, it is possible for poor configurations to allow an adversary to modify executables referenced by current Launch Daemon's plist files.

Audit

Use auditing tools capable of detecting folder permissions abuse opportunities on systems, especially reviewing changes made to folders by third-party software.

User Account Management

Limit privileges of user accounts and remediate Privilege Escalation vectors so only authorized administrators can create new Launch Daemons.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Some legitimate LaunchDaemons point to unsigned code that could be exploited. For Launch Daemons with the RunAtLoad parameter set to true, ensure the Program parameter points to signed code or executables are in alignment with enterprise policy. Some parameters are interchangeable with others, such as Program and ProgramArguments parameters but one must be present.

File: File Creation

Initial construction of a new file (ex: Sysmon EID 11)

Monitor for new files added to the /Library/LaunchDaemons/ folder. The System LaunchDaemons are protected by SIP.

File: File Modification

Changes made to a file, or its access permissions and attributes, typically to alter the contents of the targeted file (ex: Windows EID 4670 or Sysmon EID 2)

Monitor files for changes that may create or modify Launch Daemons to execute malicious payloads as part of persistence.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor for newly executed processes that may create or modify Launch Daemons to execute malicious payloads as part of persistence.

Service: Service Creation

Initial construction of a new service/daemon (ex: Windows EID 4697 or /var/log daemon logs)

Monitor for newly constructed services may create or modify Launch Daemons to execute malicious payloads as part of persistence.

Service: Service Modification

Changes made to a service/daemon, such as changes to name, description, and/or start type (ex: Windows EID 7040 or /var/log daemon logs)

Monitor services for changes made to Launch Daemons to execute malicious payloads as part of persistence.

Adversaries may create or modify Windows services to repeatedly execute malicious payloads as part of persistence. When Windows boots up, it starts programs or applications called services that perform background system functions. Windows service configuration information, including the file path to the service's executable or recovery programs/commands, is stored in the Windows Registry.

Adversaries may install a new service or modify an existing service to execute at startup in order to persist on a system. Service configurations can be set or modified using system utilities (such as sc.exe), by directly modifying the Registry, or by interacting directly with the Windows API.

Adversaries may also use services to install and execute malicious drivers. For example, after dropping a driver file (ex: .sys) to disk, the payload can be loaded and registered via Native API functions such as CreateServiceW() (or manually via functions such as ZwLoadDriver() and ZwSetValueKey()), by creating the required service Registry values (i.e. Modify Registry), or by using command-line utilities such as PnPUtil.exe. Adversaries may leverage these drivers as Rootkits to hide the presence of malicious activity on a system. Adversaries may also load a signed yet vulnerable driver onto a compromised machine (known as "Bring Your Own Vulnerable Driver" (BYOVD)) as part of Exploitation for Privilege Escalation.

Services may be created with administrator privileges but are executed under SYSTEM privileges, so an adversary may also use a service to escalate privileges. Adversaries may also directly start services through Service Execution. To make detection analysis more challenging, malicious services may also incorporate Masquerade Task or Service (ex: using a service and/or payload name related to a legitimate OS or benign software component).

Audit

Use auditing tools capable of detecting privilege and service abuse opportunities on systems within an enterprise and correct them.

Behavior Prevention on Endpoint

On Windows 10, enable Attack Surface Reduction (ASR) rules to prevent an application from writing a signed vulnerable driver to the system. On Windows 10 and 11, enable Microsoft Vulnerable Driver Blocklist to assist in hardening against third party-developed service drivers.

Code Signing

Enforce registration and execution of only legitimately signed service drivers where possible.

Operating System Configuration

Ensure that Driver Signature Enforcement is enabled to restrict unsigned drivers from being installed.

User Account Management

Limit privileges of user accounts and groups so that only authorized administrators can interact with service changes and service configurations.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor processes and command-line arguments for actions that could create or modify services. Command-line invocation of tools capable of adding or modifying services may be unusual, depending on how systems are typically used in a particular environment. Services may also be modified through Windows system management tools such as Windows Management Instrumentation and PowerShell, so additional logging may need to be configured to gather the appropriate data. Also collect service utility execution and service binary path arguments used for analysis. Service binary paths may even be changed to execute commands or scripts.

Driver: Driver Load

Attaching a driver to either user or kernel-mode of a system (ex: Sysmon EID 6)

Monitor for new service driver installations and loads (ex: Sysmon Event ID 6) that are not part of known software update/patch cycles.

Process: OS API Execution

Initial construction of a WMI object, such as a filter, consumer, subscription, binding, or provider (ex: Sysmon EIDs 19-21)

Monitor for API calls that may create or modify Windows services (ex: CreateServiceW()) to repeatedly execute malicious payloads as part of persistence.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Suspicious program execution through services may show up as outlier processes that have not been seen before when compared against historical data. Look for abnormal process call trees from known services and for execution of other commands that could relate to Discovery or other adversary techniques. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as network connections made for Command and Control, learning details about the environment through Discovery, and Lateral Movement.

Service: Service Creation

Initial construction of a new service/daemon (ex: Windows EID 4697 or /var/log daemon logs)

Creation of new services may generate an alterable event (ex: Event ID 4697 and/or 7045), especially those associated with unknown/abnormal drivers. New, benign services may be created during installation of new software.

Service: Service Modification

Changes made to a service/daemon, such as changes to name, description, and/or start type (ex: Windows EID 7040 or /var/log daemon logs)

Monitor for changes made to Windows services to repeatedly execute malicious payloads as part of persistence.

Windows Registry: Windows Registry Key Creation

Initial construction of a new Registry Key (ex: Windows EID 4656 or Sysmon EID 12)

Monitor for new constructed windows registry keys that may create or modify Windows services to repeatedly execute malicious payloads as part of persistence.

Windows Registry: Windows Registry Key Modification

Changes made to a Registry Key and/or Key value (ex: Windows EID 4657 or Sysmon EID 13|14)

Look for changes to service Registry entries that do not correlate with known software, patch cycles, etc. Service information is stored in the Registry at HKLM\SYSTEM\CurrentControlSet\Services. Changes to the binary path and the service startup type changed from manual or disabled to automatic, if it does not typically do so, may be suspicious. Tools such as Sysinternals Autoruns may also be used to detect system service changes that could be attempts at persistence.

Adversaries may bypass UAC mechanisms to elevate process privileges on system. Windows User Account Control (UAC) allows a program to elevate its privileges (tracked as integrity levels ranging from low to high) to perform a task under administrator-level permissions, possibly by prompting the user for confirmation. The impact to the user ranges from denying the operation under high enforcement to allowing the user to perform the action if they are in the local administrators group and click through the prompt or allowing them to enter an administrator password to complete the action.

If the UAC protection level of a computer is set to anything but the highest level, certain Windows programs can elevate privileges or execute some elevated Component Object Model objects without prompting the user through the UAC notification box. An example of this is use of Rundll32 to load a specifically crafted DLL which loads an auto-elevated Component Object Model object and performs a file operation in a protected directory which would typically require elevated access. Malicious software may also be injected into a trusted process to gain elevated privileges without prompting a user.

Many methods have been discovered to bypass UAC. The Github readme page for UACME contains an extensive list of methods that have been discovered and implemented, but may not be a comprehensive list of bypasses. Additional bypass methods are regularly discovered and some used in the wild, such as:

• eventvwr.exe can auto-elevate and execute a specified binary or script.

Another bypass is possible through some lateral movement techniques if credentials for an account with administrator privileges are known, since UAC is a single system security mechanism, and the privilege or integrity of a process running on one system will be unknown on remote systems and default to high integrity.

Audit

Check for common UAC bypass weaknesses on Windows systems to be aware of the risk posture and address issues where appropriate.

Privileged Account Management

Remove users from the local administrator group on systems.

Update Software

Consider updating Windows to the latest version and patch level to utilize the latest protective measures against UAC bypass.

User Account Control

Although UAC bypass techniques exist, it is still prudent to use the highest enforcement level for UAC when possible and mitigate bypass opportunities that exist with techniques such as DLL Search Order Hijacking.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments that may bypass UAC mechanisms to elevate process privileges on system.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor newly executed processes, such as eventvwr.exe and sdclt.exe, that may bypass UAC mechanisms to elevate process privileges on system.

Process: Process Metadata

Contextual data about a running process, which may include information such as environment variables, image name, user/owner, etc.

Monitor contextual data about a running process, which may include information such as environment variables, image name, user/owner that may bypass UAC mechanisms to elevate process privileges on system.

Windows Registry: Windows Registry Key Modification

Changes made to a Registry Key and/or Key value (ex: Windows EID 4657 or Sysmon EID 13|14)

Some UAC bypass methods rely on modifying specific, user-accessible Registry settings. For example:* The eventvwr.exe bypass uses the [HKEY_CURRENT_USER]\Software\Classes\mscfile\shell\open\command Registry key.* The sdclt.exe bypass uses the [HKEY_CURRENT_USER]\Software\Microsoft\Windows\CurrentVersion\App Paths\control.exe and [HKEY_CURRENT_USER]\Software\Classes\exefile\shell\runas\command\isolatedCommand Registry keys. Analysts should monitor these Registry settings for unauthorized changes.

Adversaries may delete files left behind by the actions of their intrusion activity. Malware, tools, or other non-native files dropped or created on a system by an adversary (ex: Ingress Tool Transfer) may leave traces to indicate to what was done within a network and how. Removal of these files can occur during an intrusion, or as part of a post-intrusion process to minimize the adversary's footprint.

There are tools available from the host operating system to perform cleanup, but adversaries may use other tools as well. Examples of built-in Command and Scripting Interpreter functions include del on Windows and rm or unlink on Linux and macOS.

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments for actions that could be utilized to unlink, rename, or delete files.

File: File Deletion

Removal of a file (ex: Sysmon EID 23, macOS ESF EID ES_EVENT_TYPE_AUTH_UNLINK, or Linux commands auditd unlink, rename, rmdir, unlinked, or renameat rules)

Monitor for unexpected deletion of files from the system

Adversaries may abuse msiexec.exe to proxy execution of malicious payloads. Msiexec.exe is the command-line utility for the Windows Installer and is thus commonly associated with executing installation packages (.msi). The Msiexec.exe binary may also be digitally signed by Microsoft.

Adversaries may abuse msiexec.exe to launch local or network accessible MSI files. Msiexec.exe can also execute DLLs. Since it may be signed and native on Windows systems, msiexec.exe can be used to bypass application control solutions that do not account for its potential abuse. Msiexec.exe execution may also be elevated to SYSTEM privileges if the AlwaysInstallElevated policy is enabled.

Disable or Remove Feature or Program

Consider disabling the AlwaysInstallElevated policy to prevent elevated execution of Windows Installer packages.

Privileged Account Management

Restrict execution of Msiexec.exe to privileged accounts or groups that need to use it to lessen the opportunities for malicious usage.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Command arguments used before and after the invocation of msiexec.exe may also be useful in determining the origin and purpose of the MSI files or DLLs being executed.

Module: Module Load

Attaching a module into the memory of a process/program, typically to access shared resources/features provided by the module (ex: Sysmon EID 7)

Monitor DLL/PE file events, specifically creation of these binary files as well as the loading of DLLs into processes. Look for DLLs that are not recognized or not normally loaded into a process.

Network Traffic: Network Connection Creation

Initial construction of a WMI object, such as a filter, consumer, subscription, binding, or provider (ex: Sysmon EIDs 19-21)

Monitor for newly constructed network connections that are sent or received by untrusted hosts.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Use process monitoring to monitor the execution and arguments of msiexec.exe. Compare recent invocations of msiexec.exe with prior history of known good arguments and executed MSI files.

Adversaries may bypass UAC mechanisms to elevate process privileges on system. Windows User Account Control (UAC) allows a program to elevate its privileges (tracked as integrity levels ranging from low to high) to perform a task under administrator-level permissions, possibly by prompting the user for confirmation. The impact to the user ranges from denying the operation under high enforcement to allowing the user to perform the action if they are in the local administrators group and click through the prompt or allowing them to enter an administrator password to complete the action.

If the UAC protection level of a computer is set to anything but the highest level, certain Windows programs can elevate privileges or execute some elevated Component Object Model objects without prompting the user through the UAC notification box. An example of this is use of Rundll32 to load a specifically crafted DLL which loads an auto-elevated Component Object Model object and performs a file operation in a protected directory which would typically require elevated access. Malicious software may also be injected into a trusted process to gain elevated privileges without prompting a user.

Many methods have been discovered to bypass UAC. The Github readme page for UACME contains an extensive list of methods that have been discovered and implemented, but may not be a comprehensive list of bypasses. Additional bypass methods are regularly discovered and some used in the wild, such as:

• eventvwr.exe can auto-elevate and execute a specified binary or script.

Another bypass is possible through some lateral movement techniques if credentials for an account with administrator privileges are known, since UAC is a single system security mechanism, and the privilege or integrity of a process running on one system will be unknown on remote systems and default to high integrity.

Audit

Check for common UAC bypass weaknesses on Windows systems to be aware of the risk posture and address issues where appropriate.

Privileged Account Management

Remove users from the local administrator group on systems.

Update Software

Consider updating Windows to the latest version and patch level to utilize the latest protective measures against UAC bypass.

User Account Control

Although UAC bypass techniques exist, it is still prudent to use the highest enforcement level for UAC when possible and mitigate bypass opportunities that exist with techniques such as DLL Search Order Hijacking.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments that may bypass UAC mechanisms to elevate process privileges on system.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor newly executed processes, such as eventvwr.exe and sdclt.exe, that may bypass UAC mechanisms to elevate process privileges on system.

Process: Process Metadata

Contextual data about a running process, which may include information such as environment variables, image name, user/owner, etc.

Monitor contextual data about a running process, which may include information such as environment variables, image name, user/owner that may bypass UAC mechanisms to elevate process privileges on system.

Windows Registry: Windows Registry Key Modification

Changes made to a Registry Key and/or Key value (ex: Windows EID 4657 or Sysmon EID 13|14)

Some UAC bypass methods rely on modifying specific, user-accessible Registry settings. For example:* The eventvwr.exe bypass uses the [HKEY_CURRENT_USER]\Software\Classes\mscfile\shell\open\command Registry key.* The sdclt.exe bypass uses the [HKEY_CURRENT_USER]\Software\Microsoft\Windows\CurrentVersion\App Paths\control.exe and [HKEY_CURRENT_USER]\Software\Classes\exefile\shell\runas\command\isolatedCommand Registry keys. Analysts should monitor these Registry settings for unauthorized changes.

Adversaries may set files and directories to be hidden to evade detection mechanisms. To prevent normal users from accidentally changing special files on a system, most operating systems have the concept of a ‘hidden’ file. These files don’t show up when a user browses the file system with a GUI or when using normal commands on the command line. Users must explicitly ask to show the hidden files either via a series of Graphical User Interface (GUI) prompts or with command line switches (dir /a for Windows and ls –a for Linux and macOS).

On Linux and Mac, users can mark specific files as hidden simply by putting a "." as the first character in the file or folder name. Files and folders that start with a period, ‘.’, are by default hidden from being viewed in the Finder application and standard command-line utilities like "ls". Users must specifically change settings to have these files viewable.

Files on macOS can also be marked with the UF_HIDDEN flag which prevents them from being seen in Finder.app, but still allows them to be seen in Terminal.app. On Windows, users can mark specific files as hidden by using the attrib.exe binary. Many applications create these hidden files and folders to store information so that it doesn’t clutter up the user’s workspace. For example, SSH utilities create a .ssh folder that’s hidden and contains the user’s known hosts and keys.

Adversaries can use this to their advantage to hide files and folders anywhere on the system and evading a typical user or system analysis that does not incorporate investigation of hidden files.

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor the file system and shell commands for files being created with a leading "." and the Windows command-line use of attrib.exe to add the hidden attribute.

File: File Creation

Initial construction of a new file (ex: Sysmon EID 11)

Monitor the file system and shell commands for files being created with a leading "."

File: File Metadata

Contextual data about a file, which may include information such as name, the content (ex: signature, headers, or data/media), user/ower, permissions, etc.

Monitor for contextual data about a file, which may include information such as name, the content (ex: signature, headers, or data/media), user/ower, permissions may set files and directories to be hidden to evade detection mechanisms.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Monitor newly executed processes that may set files and directories to be hidden to evade detection mechanisms.

Adversaries may employ various time-based methods to detect and avoid virtualization and analysis environments. This may include enumerating time-based properties, such as uptime or the system clock, as well as the use of timers or other triggers to avoid a virtual machine environment (VME) or sandbox, specifically those that are automated or only operate for a limited amount of time.

Adversaries may employ various time-based evasions, such as delaying malware functionality upon initial execution using programmatic sleep commands or native system scheduling functionality (ex: Scheduled Task/Job). Delays may also be based on waiting for specific victim conditions to be met (ex: system time, events, etc.) or employ scheduled Multi-Stage Channels to avoid analysis and scrutiny.

Benign commands or other operations may also be used to delay malware execution. Loops or otherwise needless repetitions of commands, such as Pings, may be used to delay malware execution and potentially exceed time thresholds of automated analysis environments. Another variation, commonly referred to as API hammering, involves making various calls to Native API functions in order to delay execution (while also potentially overloading analysis environments with junk data).

Adversaries may also use time as a metric to detect sandboxes and analysis environments, particularly those that attempt to manipulate time mechanisms to simulate longer elapses of time. For example, an adversary may be able to identify a sandbox accelerating time by sampling and calculating the expected value for an environment's timestamp before and after execution of a sleep function.

This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments that may employ various time-based methods to detect and avoid virtualization and analysis environments. Detecting actions related to virtualization and sandbox identification may be difficult depending on the adversary's implementation and monitoring required.

Process: OS API Execution

Initial construction of a WMI object, such as a filter, consumer, subscription, binding, or provider (ex: Sysmon EIDs 19-21)

Monitor for API calls that may employ various time-based methods to detect and avoid virtualization and analysis environments. Detecting actions related to virtualization and sandbox identification may be difficult depending on the adversary's implementation and monitoring required.

Process: Process Creation

Birth of a new running process (ex: Sysmon EID 1 or Windows EID 4688)

Time-based evasion will likely occur in the first steps of an operation but may also occur throughout as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as lateral movement, based on the information obtained. Detecting actions related to virtualization and sandbox identification may be difficult depending on the adversary's implementation and monitoring required. Monitoring for suspicious processes being spawned that gather a variety of system information or perform other forms of Discovery, especially in a short period of time, may aid in detection.

Adversaries may steal data by exfiltrating it over an existing command and control channel. Stolen data is encoded into the normal communications channel using the same protocol as command and control communications.

Data Loss Prevention

Data loss prevention can detect and block sensitive data being sent over unencrypted protocols.

Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level. Signatures are often for unique indicators within protocols and may be based on the specific obfuscation technique used by a particular adversary or tool, and will likely be different across various malware families and versions. Adversaries will likely change tool command and control signatures over time or construct protocols in such a way to avoid detection by common defensive tools.

Monitoring the following activities in your Organization can help you detect this technique.

Command: Command Execution

Invoking a computer program directive to perform a specific task (ex: Windows EID 4688 of cmd.exe showing command-line parameters, ~/.bash_history, or ~/.zsh_history)

Monitor executed commands and arguments that may steal data by exfiltrating it over an existing command and control channel.

File: File Access

Opening a file, which makes the file contents available to the requestor (ex: Windows EID 4663)

Monitor for suspicious files (i.e. .pdf, .docx, .jpg, etc.) viewed in isolation that may steal data by exfiltrating it over an existing command and control channel.

Network Traffic: Network Connection Creation

Initial construction of a WMI object, such as a filter, consumer, subscription, binding, or provider (ex: Sysmon EIDs 19-21)

Monitor for newly constructed network connections that are sent or received by untrusted hosts.

Network Traffic: Network Traffic Content

Logged network traffic data showing both protocol header and body values (ex: PCAP)

Monitor and analyze traffic patterns and packet inspection associated to protocol(s) that do not follow the expected protocol standards and traffic flows (e.g extraneous packets that do not belong to established flows, gratuitous or anomalous traffic patterns, anomalous syntax, or structure). Consider correlation with process monitoring and command line to detect anomalous processes execution and command line arguments associated to traffic patterns (e.g. monitor anomalies in use of files that do not normally initiate connections for respective protocol(s)).

Network Traffic: Network Traffic Flow

Summarized network packet data, with metrics, such as protocol headers and volume (ex: Netflow or Zeek http.log)

Monitor network data for uncommon data flows. Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.