Malicious RTF — malware analysis report

Static analysis result for SHA-256 fa55909353b8954d…

MALICIOUS

RTF

10.2 KB First seen: 2023-01-10
MD5: 8000873a9b409001877da726967a367f SHA-1: feb7158cf09350816569804b42dfbe2a37d0ff8c SHA-256: fa55909353b8954d01c3cc785ccf4b3ac295d29e20bf176a1f3949aac29ad2db
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics indicates that the embedded object is designed to be automatically activated upon opening the document. This activation likely leads to the execution of malicious code, consistent with exploiting this known vulnerability to download and execute a secondary payload.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • 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_off00001a8a.bin
dd868032314eb597445d7417111e5366f734696592bc7ff8c1804f5f711ecd84		 rtf-objdata-decoded RTF \objdata at offset 0x1A8A 1757 bytes

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