Malicious RTF — malware analysis report

Static analysis result for SHA-256 2283dcec06c9d9e4…

MALICIOUS

RTF

1.10 MB Authoring application: Riched20 6.3.9600 First seen: 2021-06-17
MD5: 5c46707e88bff8cef36f4ca0fc3dbd70 SHA-1: 5f58a4c551bb57761e875c60b3181c3c0068d8b5 SHA-256: 2283dcec06c9d9e43d17af0597a2160b2097fdd1d771170829ebec5d639dbbd1
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 Microsoft Equation Editor, triggering critical heuristics for RTF_OBJCLASS_EQUATION and RTF_EQUATION_EDITOR. The presence of \objupdate indicates that the embedded object is forced to activate, leading to the exploitation of CVE-2018-0802. This exploit allows for arbitrary code execution, commonly used to deliver secondary payloads.

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 17186 bytes
SHA-256: 279854938cf189b64a51d326552cfdfefb981afea1a74e50dc96811fb0f8a757

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