Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 3f7a2bb1fec9ba3d…

MALICIOUS

RTF / .DOC

18.5 KB First seen: 2022-10-11
MD5: 335d4b762415e79ecdf6267625ddf3d0 SHA-1: a22edece64e92a06714fef96fd19ac367ed9b7c6 SHA-256: 3f7a2bb1fec9ba3d939367d1ebccf666711e3ca4feda0501d40cf6760e7cc706
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute code. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates exploitation of this specific vulnerability. The `SE_ENABLE_LURE` heuristic suggests the document contains a social engineering element to trick the user into enabling content, which is a common delivery method 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_off00000e00.bin
2dff2c947aaaacd378656392ae67ad1ee2a376a7a3da706aa90b9bb5f7f6634e		 rtf-objdata-decoded RTF \objdata at offset 0xE00 1696 bytes

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