Malicious RTF — malware analysis report

Static analysis result for SHA-256 6c6e129561879c25…

MALICIOUS

RTF

15.9 KB First seen: 2023-02-15
MD5: f470816cd792428533d9869f55805ee6 SHA-1: ea7793e02551d88118e47038fc1f26c669817f6f SHA-256: 6c6e129561879c25417e511a8a3c683b33375c05167285f1d81972df70a414d6
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1559 Component Object Model Hijacking T1059 Command and Scripting Interpreter

The RTF document contains an OLE object that is automatically linked and updated, triggering Equation Editor. Heuristics indicate this is related to CVE-2017-11882, a known vulnerability used for arbitrary code execution. The embedded OLE object data is the primary indicator of compromise.

Heuristics 5

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • 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 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000017ca.bin
66c89691cea9f56c68db882e2de5b2d3629c54f6dd62857aa240f4e0897ade97		 rtf-objdata-decoded RTF \objdata at offset 0x17CA 2167 bytes

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