Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 21c8292c582ef187…

MALICIOUS

RTF / .DOC

5.8 KB First seen: 2022-12-08
MD5: f6bd079e11ada7e0eaf1fe11727a7a8a SHA-1: 1f68c6b344d0308ce6b1061c7cc1f44462e626a9 SHA-256: 21c8292c582ef187d7b1a6cf8241a498b89ceb5bb585ba430158581990fbbfa5
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

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 includes a lure instructing the user to enable editing and content, a common tactic for macro-based malware droppers. The exploit facilitates the execution of arbitrary code, likely leading to a second-stage payload.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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_off000007e1.bin
26e93b6e4dc8ec35f6c1ff738522f41a5c2dd7713fa2fe9d85208132532cb2b2		 rtf-objdata-decoded RTF \objdata at offset 0x7E1 1908 bytes

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