Malicious RTF — malware analysis report

Static analysis result for SHA-256 c7dc6b2bd9dffd55…

MALICIOUS

RTF

241.6 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-17
MD5: 73877c0038f1dc67e2c0b79204f22636 SHA-1: 9c08caf973e02fe55167ff1278b1775b1954c553 SHA-256: c7dc6b2bd9dffd5545aa639f622a3f565d049a1c06e1536b00535888f8c2fd6e
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 an Equation Editor object, triggering critical heuristics related to Equation Editor exploitation. This strongly suggests the file is designed to exploit CVE-2018-0802, a known vulnerability in Microsoft Equation Editor, to achieve arbitrary code execution. The ClamAV detection further confirms its malicious nature as Rtf.Exploit.CVE_2018_0802-6624871-1.

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 12332 bytes
SHA-256: 3d1bd11da0f07da191ea1403fc66bfbf1d82e4590c8a8c4893baeedac25b9aa3

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