Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 79ea6813fdcca94e…

MALICIOUS

RTF / .DOC

26.2 KB First seen: 2022-11-07
MD5: 099e38578c381bf83bb9d20e8375148c SHA-1: 86bbb5077a9427bcab72c9e02bbf180b57803ee3 SHA-256: 79ea6813fdcca94e123769b9adf3d287efd5a9c40eb390718a5b15948176ba3f
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 that contains an embedded OLE object, specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The 'SE_ENABLE_LURE' heuristic indicates that the document prompts the user to enable editing, a common tactic for malware droppers. The embedded object's ProgID, 'eqUatiOn.3', is a strong indicator of this specific exploit.

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_off0000527a.bin
cf7e3a27c5e6d713c10a062d7abd2fa5a7746a359f120185e8b4f8b65e530207		 rtf-objdata-decoded RTF \objdata at offset 0x527A 1590 bytes

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