Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 6f0318fc63a3a123…

MALICIOUS

RTF / .DOC

8.3 KB First seen: 2023-02-01
MD5: a8caccc115c0ee90a947c31c8e3a452a SHA-1: 42324c751619e2217c9879cb6bc312061d56639b SHA-256: 6f0318fc63a3a123bc36c8c9765852b56ab83083a2f0c1338d8d3493e7273802
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The RTF document contains OLE object data specifically crafted to exploit the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this exploit. The ".objupdate" directive further ensures OLE object activation, 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_off000012f6.bin
80d599af0edf87c4c6affbbb7a0f31aae27df391e42029d6e56d3cba5150bd32		 rtf-objdata-decoded RTF \objdata at offset 0x12F6 1791 bytes

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