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}"
| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| action.hacking.variety.Abuse of functionality | Abuse of functionality. | related-to | T1216.002 | System Script Proxy Execution: SyncAppvPublishingServer |
| Capability ID | Capability Description | Mapping Type | ATT&CK ID | ATT&CK Name | Notes |
|---|---|---|---|---|---|
| cloud_identity | Cloud Identity | technique_scores | T1216.002 | SyncAppvPublishingServer |
Comments
The access controls in Cloud Identity, such as MFA, can help to prevent an adversary from accessing internal software such as SyncAppvPublishingServer, protecting customer data. However, if the adversary is able to access the system, Cloud Identity is not able to protect this data, leading to a score of partial.
References
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