Malicious RTF — malware analysis report

Static analysis result for SHA-256 8b5a7b79e5537e3f…

MALICIOUS

RTF

80.6 KB First seen: 2023-08-08
MD5: 822ca31c5b8abc31d5b81fa02278907f SHA-1: a105e79b85f8bb3c7c66a50af1c7b3f8a21ef5ea SHA-256: 8b5a7b79e5537e3f9bc64570f0671948ca33f7a8c979e74be718669c1e20f075
140 Risk Score

Malware Insights

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

The sample is an RTF document that leverages the Equation Editor vulnerability, indicated by the RTF_EQUATION_EDITOR and RTF_OBJUPDATE heuristics. It contains a lure in the document body instructing the user to 'Enable editing', which is a common technique to bypass macro security settings and trigger the exploit. The embedded OLE object data further supports the exploitation attempt.

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_off00004d24.bin
f167c748e25306d50a9dec00240b1590e0f9cd8a9fcc2da4ca747882721c8771
rtf-objdata-decoded RTF \objdata at offset 0x4D24 1957 bytes