BURNBOOK DLL Sideloading via SumatraPDF.exe Loading libmupdf.dll from User Directory (via image_load)

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 SumatraPDF.exe loading a libmupdf.dll from a user-writable directory such as Downloads or Temp, the DLL side-loading behavior used to launch the BURNBOOK loader delivered in a ZIP archive during Operation DreamJob intrusions. Adversaries pair a benign PDF reader with a malicious library to execute their loader under a trusted process.

Reporting behind it

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BURNBOOK DLL Sideloading via SumatraPDF.exe Loading libmupdf.dll from User Directory (via image_load)

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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