Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c03b8b868c7a682d…

MALICIOUS

RTF / .DOC

2.21 MB
MD5: 92aeeaec0040bcd3a4a9f355ef8ad81e SHA-1: 3b9e8ac2df95588213252701f10ba1446b1ce58b SHA-256: c03b8b868c7a682d9b1a09c529230ecaecc440debaed302e32cd81b0b86b8798
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The sample is an RTF document that contains embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. The presence of ".objupdate" indicates that the OLE object is set to automatically activate, leading to the exploitation of the Equation Editor vulnerability. This allows for arbitrary code execution, likely to download and run a secondary payload.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001202.bin
7999bb3508fcadcfc4144ed54785aaeb8089e8d9abe61d3d357de4a38b080aff		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27201 bytes
objdata_01_off0001ca43.bin
1a9daf7f5259077ae9a7fba5e35fb7f5d70b6d43574b5a4ed8dc4e9c9ad184d1		 rtf-objdata-decoded RTF \objdata at offset 0x1CA43 475057 bytes

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