User Execution

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User Execution
Technique
ID T1204
Tactic Execution
Platform Linux, Windows, macOS
Permissions Required User
Data Sources Anti-virus, Process command-line parameters, Process monitoring

An adversary may rely upon specific actions by a user in order to gain execution. This may be direct code execution, such as when a user opens a malicious executable delivered via Spearphishing Attachment with the icon and apparent extension of a document file. It also may lead to other execution techniques, such as when a user clicks on a link delivered via Spearphishing Link that leads to exploitation of a browser or application vulnerability via Exploitation for Client Execution. While User Execution 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.

Examples

  • APT28 attempted to get users to click on Microsoft Excel attachments containing malicious macro scripts.1
  • APT29 has used various forms spearphishing attempting to get a user to open links or attachments. 2
  • APT37 has sent spearphishing attachments attempting to get a user to open them.3
  • Elderwood has leveraged multiple types of spearphishing in order to attempt to get a user to open links and attachments.45
  • FIN8 has leveraged both Spearphishing Link and Spearphishing Attachment attempting to gain User Execution.678
  • Leviathan has sent spearphishing emails links and attachments attempting to get a user to click.9
  • Magic Hound has attempted to get users to execute malware via social media and spearphishing emails.10
  • PLATINUM has attempted to get users to open malicious files by sending spearphishing emails with attachments to victims.11
  • TA459 has attempted to get victims to open malicious Microsoft Word attachment sent via spearphishing.12
  • menuPass has attempted to get victims to open malicious files sent via email as part of spearphishing campaigns.1314

Mitigation

Use user training as a way to bring awareness to common phishing and spearphishing techniques and how to raise suspicion for potentially malicious events. Application whitelisting may be able to prevent the running of executables masquerading as other files.

If a link is being visited by a user, block unknown or unused files in transit by default that should not be downloaded or by policy from suspicious sites as a best practice to prevent some vectors, such as .scr, .exe, .pif, .cpl, etc. Some download scanning devices can open and analyze compressed and encrypted formats, such as zip and rar that may be used to conceal malicious files in Obfuscated Files or Information.

If a link is being visited by a user, network intrusion prevention systems and systems designed to scan and remove malicious downloads can be used to block activity. Solutions can be signature and behavior based, but adversaries may construct files in a way to avoid these systems.

Detection

Monitor the execution of and command-line arguments 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.

Anti-virus can potentially detect malicious documents and files that are downloaded and execuited 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) for techniques such as Exploitation for Client Execution and Scripting.

References