Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8741d5ed80b4390b…

MALICIOUS

RTF / .DOC

222.1 KB First seen: 2022-02-22
MD5: 7d447ae610e921fc6e5473dafd8e3ddb SHA-1: 11c1f8dbbb7f8e0e9bb23fdb99e2da467d62c876 SHA-256: 8741d5ed80b4390b11897114ce6cb74af88cc857f0e3f0ba7d530edaff2a1b3d
200 Risk Score

Malware Insights

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

The sample is an RTF document containing embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. This indicates the document is designed to exploit a known vulnerability in Microsoft Equation Editor to achieve arbitrary code execution upon opening. No further stages or IOCs were extracted from this sample.

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_off0000009c.bin
0ae9d8674a7c9d1b45e6e5236b0048fcea779df1d8e7b0af3ea208834854048b		 rtf-objdata-decoded RTF \objdata at offset 0x9C 70471 bytes

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