Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 0b9dbebe4e5cff5b…

MALICIOUS

RTF / .DOC

135.1 KB First seen: 2022-03-10
MD5: 8932906ce4bf47c8ad9ab82aaf246052 SHA-1: 051782adbb37f5ca245e6ee1616686684ea9a4d5 SHA-256: 0b9dbebe4e5cff5ba2aed97cb1168de2e5435b8e64f9c0344ed7910432f2aa9a
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains embedded OLE object data, specifically related to Microsoft Equation Editor. Heuristics indicate the exploitation of CVE-2017-11882, which allows for arbitrary code execution when the embedded object is activated. The presence of ".objupdate" further suggests an attempt to force OLE object activation.

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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000a6.bin
fbfbd016f0fdb53e8bb5e06d342e28767db45a0e9b50ffb66dfa22507c0474b2
rtf-objdata-decoded RTF \objdata at offset 0xA6 39821 bytes