Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b97cb5a8f5db4bbb…

MALICIOUS

RTF / .DOC

28.0 KB First seen: 2022-11-30
MD5: 5b0ebe022ab24730162fd5c38729d9d8 SHA-1: c0bd9604f737f6ffaf65b85557c071645caf461e SHA-256: b97cb5a8f5db4bbb429974beeb3adbac796689747a63058846c3407672434fff
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 PowerShell

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to achieve code execution. The presence of OLE object data and specific Equation Editor ProgIDs strongly indicates this exploit. The document also contains a lure to enable editing, a common tactic for macro-based malware.

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.
  • 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
  • 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_off00005c6e.bin
1b2180826ec1eadea6538010a5a822c695896abdc4c15a5db1cd39aa979c1dc8		 rtf-objdata-decoded RTF \objdata at offset 0x5C6E 1395 bytes

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