Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 4896a1d4fa2680e2…

MALICIOUS

RTF / .DOC

31.3 KB First seen: 2022-12-23
MD5: b55f101e9b36bc79c44cd7c0fa7bffc8 SHA-1: 1734ce90cc8c0fb6fe9fbd4818bfe796f1f17fe6 SHA-256: 4896a1d4fa2680e25f8bcdf0c171078d1ba008a7f5e4299559e7e2528dedd18c
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 T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability by embedding a malicious Equation Editor object. The document body contains a lure related to marketing strategy, likely to trick the user into enabling content. The critical heuristic firing for CVE_2017_11882_ACTIVATION_RELATED confirms the exploit attempt, which is designed to execute arbitrary code.

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_off00005ad6.bin
78a503b4b06b89c950f657d1cac376a90c4d7c69c4676fcdbe33873c01706c1f		 rtf-objdata-decoded RTF \objdata at offset 0x5AD6 1948 bytes

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