Malicious USERENV.dll Sideloaded by AppVShNotify.exe

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.001DLL
Persistence
- T1574.001DLL
Priv Esc
- T1574.001DLL
Defense Evasion
- T1574.001DLL
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects AppVShNotify.exe loading a USERENV.dll from outside the System32 directory which indicates DLL search-order hijacking. Lazarus abused this signed Microsoft binary during Operation SyncHole to sideload a malicious loader DLL. A userenv module resolved from a non-system path is the hallmark of the sideloading chain.

Reporting behind it

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Malicious USERENV.dll Sideloaded by AppVShNotify.exe

Pivot detection · T1574.001 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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