Malicious RTF — malware analysis report

Static analysis result for SHA-256 48409e947d39bc1a…

MALICIOUS

RTF

3.0 KB First seen: 2022-12-13
MD5: 3baaa80b405e586b607cd77db4adf163 SHA-1: 6e8e60717d32b6466e67b05a0a9752fc8c5cd807 SHA-256: 48409e947d39bc1ad581261fe26ced3ea8b487ab1c109c55ce3fb7bab2c54c82
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an OLE object that leverages a known vulnerability in Microsoft Equation Editor (CVE-2017-11882). The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates exploitation of this vulnerability. The `RTF_OBJUPDATE` heuristic suggests that the OLE object is designed to activate automatically, leading to arbitrary code execution.

Heuristics 5

  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000077.bin
dc2291de9604cea294eaca2a46c8466a981a8d4645598020b764f8f2a0993ad2		 rtf-objdata-decoded RTF \objdata at offset 0x77 1410 bytes

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