Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b837356985ee9e15…

MALICIOUS

RTF / .DOC

73.3 KB First seen: 2023-09-14
MD5: d76c8672638bc36617dfa2a84ee47e1a SHA-1: b32b3c50b37d764fc0c74da31f7f7cb60b715ebd SHA-256: b837356985ee9e1513bc8f6e05a0678df466a725d5b10ee593ee2b5d90897438
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution T1204.002 Malicious File T1566 Phishing T1566.001 Spearphishing Attachment T1059 Command and Scripting Interpreter T1059.005 Visual Basic

The sample is an RTF document that leverages OLE object data and an Equation Editor exploit, indicated by the RTF_OBJDATA, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristic firings. The document body contains text about financial auditing and includes a lure to 'Enable editing', suggesting a social engineering tactic to bypass security measures and execute the embedded malicious object. No scripts were extracted, and the specific exploit mechanism is not detailed beyond the OLE object.

Heuristics 4

  • 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
  • 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_off00003f7b.bin
30afe156a84443e2a3049e9252f12b468ef85579fe224cb750d76ee510bc0b74
rtf-objdata-decoded RTF \objdata at offset 0x3F7B 2062 bytes