Malicious RTF — malware analysis report

Static analysis result for SHA-256 77b8f47335559f02…

MALICIOUS

RTF

239.9 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-20
MD5: 8085706cbc1e8e62fefafe15ddfdfc8c SHA-1: bab7986d3a50c637ad9295d32adc9123888f3a77 SHA-256: 77b8f47335559f023b7346b0b215a53e6a703203505c10e0f3a3b89981e9f166
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 exploitation. The ClamAV detection name 'Rtf.Exploit.CVE_2018_0802-6624871-1' strongly suggests exploitation of a known vulnerability in the Equation Editor component. This indicates the file is designed to execute arbitrary code upon opening, likely delivered 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000100.bin rtf-objdata-decoded RTF \objdata at offset 0x100 16867 bytes
SHA-256: 4e6cdb440c7b855b53fad37c4b97626083167e83eecfce18d36e4105b80cd2ab