Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 61e8cb3e66f40db8…

MALICIOUS

RTF / .DOC

23.4 KB
MD5: b5bf6462cf600dc7234862d5592272df SHA-1: 7f48eba9089e8d2552102a0f12374d9bcbc615e9 SHA-256: 61e8cb3e66f40db85b67a73d6a82135f60ef2d477feeb073686e32aaba072607
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document that contains embedded OLE object data, specifically targeting Microsoft Equation Editor. Heuristics indicate the exploitation of CVE-2017-11882, which allows for arbitrary code execution. This technique is commonly used to download and execute further malicious stages. The specific class name 'EquAtIoN.3' is identified as a key indicator.

Heuristics 5

  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001a5e.bin
b1d72d08929b69ce421a5533754fb89bef19ebb717728ad8c1934d8a34c52083		 rtf-objdata-decoded RTF \objdata at offset 0x1A5E 2007 bytes

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