Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 1cc7491b728e635c…

MALICIOUS

RTF / .DOC

30.2 KB First seen: 2022-12-07
MD5: 598cd4333e3a0b3ceae30795a0189ea5 SHA-1: c6951e9e3f5c41fc752dcd981315c610cb104bfe SHA-256: 1cc7491b728e635cce8087763006f4384c715f2a84c3472fed392a15a0aa3bb6
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model Hijacking

The sample is an RTF document that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The heuristic firings indicate the presence of an OLE object and specific activation-related indicators for this CVE. The document body contains a lure to 'Enable editing', a common tactic for macro-enabled documents, though no macros were explicitly extracted. The primary IOC is the Equation Editor class name, which is indicative of the 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.
  • 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_off00004b7b.bin
cce0098d14f2d11fc96a2c065a7931d829c0fb77bdc4fd8e9bd149eb28514d9b		 rtf-objdata-decoded RTF \objdata at offset 0x4B7B 1888 bytes

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