T1216.002 SyncAppvPublishingServer — Attack Pattern

Description

Adversaries may abuse SyncAppvPublishingServer.vbs to proxy execution of malicious PowerShell commands. SyncAppvPublishingServer.vbs is a Visual Basic script associated with how Windows virtualizes applications (Microsoft Application Virtualization, or App-V).(Citation: 1 - appv) For example, Windows may render Win32 applications to users as virtual applications, allowing users to launch and interact with them as if they were installed locally.(Citation: 2 - appv)(Citation: 3 - appv) The SyncAppvPublishingServer.vbs script is legitimate, may be signed by Microsoft, and is commonly executed from `\System32` through the command line via `wscript.exe`.(Citation: 4 - appv)(Citation: 5 - appv) Adversaries may abuse SyncAppvPublishingServer.vbs to bypass PowerShell execution restrictions and evade defensive counter measures by "living off the land."(Citation: 6 - appv)(Citation: 4 - appv) Proxying execution may function as a trusted/signed alternative to directly invoking `powershell.exe`.(Citation: 7 - appv) For example, PowerShell commands may be invoked using:(Citation: 5 - appv) `SyncAppvPublishingServer.vbs "n; {PowerShell}"`

MITRE ATT&CK Detection Strategies
1

DET0440 Detecting PowerShell Execution via SyncAppvPublishingServer.vbs Proxy Abuse

AN1220 Windows

Execution of SyncAppvPublishingServer.vbs through wscript.exe with a command-line containing embedded PowerShell, proxying malicious PowerShell execution through a Microsoft-signed VBScript interpreter to evade detection and restrictions.

WinEventLog:Sysmon WinEventLog:PowerShell WinEventLog:Sysmon WinEventLog:Sysmon

MITRE ATT&CK Mitigations
1

M1038

Execution Prevention

Prevent the execution of unauthorized or malicious code on systems by implementing application control, script blocking, and other execution prevention mechanisms. This ensures that only trusted and authorized code is executed, reducing the risk of malware and unauthorized actions. This mitigation can be implemented through the following measures: Application Control: - Use Case: Use tools like AppLocker or Windows Defender Application Control (WDAC) to create whitelists of authorized applications and block unauthorized ones. On Linux, use tools like SELinux or AppArmor to define mandatory access control policies for application execution. - Implementation: Allow only digitally signed or pre-approved applications to execute on servers and endpoints. (e.g., `New-AppLockerPolicy -PolicyType Enforced -FilePath "C:\Policies\AppLocker.xml"`) Script Blocking: - Use Case: Use script control mechanisms to block unauthorized execution of scripts, such as PowerShell or JavaScript. Web Browsers: Use browser extensions or settings to block JavaScript execution from untrusted sources. - Implementation: Configure PowerShell to enforce Constrained Language Mode for non-administrator users. (e.g., `Set-ExecutionPolicy AllSigned`) Executable Blocking: - Use Case: Prevent execution of binaries from suspicious locations, such as `%TEMP%` or `%APPDATA%` directories. - Implementation: Block execution of `.exe`, `.bat`, or `.ps1` files from user-writable directories. Dynamic Analysis Prevention: - Use Case: Use behavior-based execution prevention tools to identify and block malicious activity in real time. - Implemenation: Employ EDR solutions that analyze runtime behavior and block suspicious code execution.

SyncAppvPublishingServer

Description

MITRE ATT&CK Detection Strategies 1

MITRE ATT&CK Mitigations 1

Details

MITRE ATT&CK Detection Strategies
1

MITRE ATT&CK Mitigations
1