Malicious RTF — malware analysis report

Static analysis result for SHA-256 ad430c481c0f5a52…

MALICIOUS

RTF

276.4 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-17
MD5: 86e46a784249d8ed7ead680bd0389263 SHA-1: 8bbf4212c4bb4e76e93b5aac07a896a9cb7b9208 SHA-256: ad430c481c0f5a5200257cc473129223be37cc13c8c0712bcef3b6e12f0f12ec
240 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object specifically identified as a Microsoft Equation Editor object, which is known to be vulnerable. The presence of \objupdate and \objdata sections strongly suggests that this object is designed to be activated, leading to the exploitation of CVE-2018-0802 for client execution. This is a common technique for delivering malicious payloads via spearphishing attachments.

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 16896 bytes
SHA-256: 51cb1187ff65b7e1d47f3c9121ae354c67d10cca1aa62a94321102b838e34ad5