Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 3cf83d826c47b887…

MALICIOUS

RTF / .DOC

23.5 KB First seen: 2022-11-30
MD5: 4c6aaef387645227a1a987043d56d6be SHA-1: feaec8f7f4652115ee34e2eae79987778ca87de9 SHA-256: 3cf83d826c47b887733f5f279e16936e9fa36efb6ad6badd5b1fb3aaeeb43a2f
220 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object designed to exploit the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The document body includes a lure instructing the user to 'Enable editing', which, if clicked, would trigger the exploit. This exploit allows for arbitrary code execution, likely to download and run a second-stage payload.

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_off00004380.bin
17cc5d4bb4146bfb28e583a2d20b44bd6edaa66b6646f627a4bd145ccedbb2b3		 rtf-objdata-decoded RTF \objdata at offset 0x4380 1933 bytes

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