Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c45da0b05119c365…

MALICIOUS

RTF / .DOC

29.2 KB First seen: 2022-11-17
MD5: 2c64732dfe602b067156603124829edf SHA-1: 0eef000a797ac1f1ebe20fa88c1be2c611c011ad SHA-256: c45da0b05119c365662c070a6f22ef0a1ce02ef10692276e9a3c93694d064077
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 T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1566.002 Phishing: Spearphishing Link

The file is an RTF document containing an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics confirms this. The `SE_ENABLE_LURE` heuristic indicates the document likely contains a social engineering prompt to enable editing or macros, a common technique for malware droppers. The exploit is designed to execute arbitrary code, typically to download and run a secondary 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_off00005969.bin
34c2b45bef893ab5f6d590491d5885ebf4e3fa9ca5b36bba3849f0d836d8badf		 rtf-objdata-decoded RTF \objdata at offset 0x5969 1547 bytes

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