Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7c9a232eaf99f7fb…

MALICIOUS

RTF / .DOC

73.5 KB First seen: 2023-08-17
MD5: c01c96ba7765c7b8190bb76aab9d647f SHA-1: b142abe8075c13fe1476d095a2980f67ebd4d699 SHA-256: 7c9a232eaf99f7fbb83cb964272b889f0e5b27176c556394f317c6dce3745f9b
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution T1204.002 User Execution: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document that contains OLE object data and specifically triggers heuristics related to the Equation Editor vulnerability. The document body includes a lure instructing the user to 'click Enable editing', which is a common tactic for macro-based malware. The presence of RTF_EQUATION_EDITOR and RTF_OBJUPDATE strongly suggests exploitation of a known Equation Editor vulnerability to execute arbitrary code, likely to download and run a second-stage payload.

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.
  • \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
  • 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_off00002e2e.bin
b773448085e52681c7d36b2e12e43dd2c921d541c59d51fac2c95569c921060d
rtf-objdata-decoded RTF \objdata at offset 0x2E2E 1432 bytes