Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 ac3bb4fb231f894a…

MALICIOUS

RTF / .DOC

33.6 KB First seen: 2023-02-03
MD5: 5acaa24c5a115003f5833bbb9b175d61 SHA-1: 72094cc184a5dc1b96594e2e66a9c09f6d7b997d SHA-256: ac3bb4fb231f894a3b028a696211dd9ec91718ae8a677e328077beca1ca0baf9
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability. The document body includes a lure instructing the user to 'Enable editing', a common tactic for macro-based malware. The presence of RTF_EQUATION_EDITOR and RTF_OBJUPDATE heuristics strongly indicates exploitation of this known vulnerability to achieve code execution.

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_off000043d1.bin
390a6aa9fef4c99b9ac89af8870c74c10a8b5304c9e550b387719aebb4ad9569
rtf-objdata-decoded RTF \objdata at offset 0x43D1 1606 bytes