Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 067e3cd1452fb423…

MALICIOUS

RTF / .DOC

4.1 KB First seen: 2022-04-08
MD5: 6c0b88c58bbcbb51c8541dff4af23a38 SHA-1: 723e31a0b0a1ebf48bc1bb042ff1455d51c92f9f SHA-256: 067e3cd1452fb423bdf0bbde1a618397c76c06ab2445e367d177f1a8818c7758
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an RTF document that contains embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. This indicates the document is designed to exploit this known vulnerability for arbitrary code execution upon opening. The presence of ".objupdate" further suggests forced OLE activation, reinforcing the exploitation attempt.

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_off00000099.bin
f2d2bef813a4f7f554593dbb2c378d9bdeb1f0b9317f7aba441994b824446928		 rtf-objdata-decoded RTF \objdata at offset 0x99 1836 bytes

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