Suspicious WindowsCodecs DLL Sideload from Non System Path by Fighting Ursa

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 WindowsCodecs.dll being loaded from a location outside the Windows system directories, the DLL search order hijack Fighting Ursa uses when a renamed calc.exe sideloads a malicious copy to run its batch payload. Loading a system DLL name from a user path indicates sideloading rather than legitimate use. Detecting this exposes the sideload stage of the infection.

Reporting behind it

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Suspicious WindowsCodecs DLL Sideload from Non System Path by Fighting Ursa

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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