Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 cf8fdb9fab9c9d61…

MALICIOUS

RTF / .DOC

29.1 KB First seen: 2022-11-08
MD5: 3ef8b9725a4ced1ecd9bbdfeba3bb266 SHA-1: 0c7b45c6bab02f9e974b9d8f845d1fc931704e69 SHA-256: cf8fdb9fab9c9d61021ab8402d02fd034f400fd288fd3de40c52f447b4f11261
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 specifically identified as related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of RTF_OBJDATA, RTF_OBJEMB, and RTF_EQUATION_EDITOR heuristics strongly indicates exploitation of this vulnerability. The document also contains a lure instructing the user to 'Enable editing', a common tactic for macro-based or exploit-based document attacks.

Heuristics 6

  • 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.
  • \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_off00005c1a.bin
4664d496ab39c646ee9d9a3957a32b29a844fd5b93889d5b99eac10f221d306d		 rtf-objdata-decoded RTF \objdata at offset 0x5C1A 1733 bytes

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