Malicious RTF — malware analysis report

Static analysis result for SHA-256 d345dff17f30b0dd…

MALICIOUS

RTF

276.0 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-17
MD5: c95e95f70bd8b0fc8281258f38453a88 SHA-1: 9d3eb413628421634b3a807c67b94b02c9a7c861 SHA-256: d345dff17f30b0dd4bd2e7894f4f2dfd89f5b1dc403216639073b184efb6ba21
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. High-severity heuristics indicate the use of ".objupdate" to force OLE activation and the presence of the Equation Editor object class. ClamAV detection confirms this as Rtf.Exploit.CVE_2018_0802-6624871-1, a known exploit targeting a vulnerability in the Equation Editor component, likely leading to arbitrary code execution.

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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000100.bin rtf-objdata-decoded RTF \objdata at offset 0x100 13887 bytes
SHA-256: e8512c25ad533d1da20de57105377e8c854da58371a2fca4a8a8587372a720ba

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