Malicious RTF — malware analysis report

Static analysis result for SHA-256 cab228743ee79346…

MALICIOUS

RTF

166.9 KB First seen: 2023-10-25
MD5: 16623c0aad5fed9044f5be6033884824 SHA-1: 58c1b73a84c58c930f3010386120bb1dd5eb3a4d SHA-256: cab228743ee793465f69d12bbdb37eb2567f389d851ce7dac62bcc9fe39e8a6b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The sample is an RTF document that leverages OLE object embedding, specifically targeting the Equation Editor vulnerability (RTF_EQUATION_EDITOR). The document body contains a lure explaining internal controls and auditors' opinions, instructing the user to 'enable editing from the yellow bar above', which is a common tactic to bypass security measures. The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE further indicates the automatic activation of embedded OLE objects, likely to exploit the Equation Editor.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000035bc.bin
6d0b52705ecd1ac3f332b5517cd270d7115e89e6d5ab8fcfc94cb90b7510bca7		 rtf-objdata-decoded RTF \objdata at offset 0x35BC 1886 bytes

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