Malicious RTF — malware analysis report

Static analysis result for SHA-256 bc4063c3f3c5bb4f…

MALICIOUS

RTF

277.0 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-17
MD5: 1401ad828ea63ccc1758a85d80947599 SHA-1: 1139b31036443ec89e38d05c5985fee51b4af7c0 SHA-256: bc4063c3f3c5bb4fbacbe353a8e6343675e7842e12a31e59dcaeeac62af960a9
240 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects, specifically identified as Microsoft Equation Editor. Heuristics indicate that \objupdate forces OLE activation, and the object class is Equation Editor, strongly suggesting exploitation of CVE-2018-0802. This vulnerability allows for arbitrary code execution when the document is opened, likely as a spearphishing attachment.

Heuristics 6

  • ClamAV: Rtf.Exploit.CVE_2018_0802-6624871-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2018_0802-6624871-1
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • Equation Editor ProgID + OLE object high RTF_EQUATION_EDITOR
    RTF references Equation.3 ProgID alongside \objdata — likely Equation Editor (CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798) but without the binary CLSID payload, so flagged at HIGH instead of CRITICAL.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

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