Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b14d52ef578d1726…

MALICIOUS

RTF / .DOC

9.5 KB First seen: 2022-09-20
MD5: 64d9a5dbdab5d7dabb7e4326a8187ede SHA-1: d126132d21bbe6c54a21ba011e877825ac19a38f SHA-256: b14d52ef578d17267df4a954b86ce859e7d97b61cea3132380d0a624d68776c7
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution T1204.002 Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking T1187 Exploitation for Client Execution T1059 Command and Scripting Interpreter

The sample is an RTF document containing an embedded OLE object that exploits CVE-2017-11882 via the Equation Editor (EqUation.3). The document body contains a lure instructing the user to 'Enable editing' to view the content. The RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics indicate that the embedded object is automatically activated upon opening, facilitating the exploitation.

Heuristics 6

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000014a4.bin
b66c5f5f47556b00db5cc6483eda701fac4b76b5a877b3af58c2a414da70b2f9		 rtf-objdata-decoded RTF \objdata at offset 0x14A4 1536 bytes

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