Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 41ce21307d23c24f…

MALICIOUS

RTF / .DOC

26.2 KB First seen: 2023-10-23
MD5: 709ec3fb8ef86c14875523526851e709 SHA-1: 3f74baca899772a3a7da32041ad0c78d8a171dd5 SHA-256: 41ce21307d23c24f931acaedf675b008f9b91277b166c0e301b19a54b29b62c2
120 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1204.002 Malicious File

The RTF document contains embedded OLE object data and specifically triggers the Equation Editor vulnerability. The ".objupdate" directive forces the activation of this embedded object, leading to code execution. This is a common technique for delivering secondary payloads, though no specific payload or download URL was directly extracted from this sample.

Heuristics 3

  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001386.bin
4a6dccfd4117f3b1d9f1f88f378a786b4bb38a0e535dc978624d4b6d74fc18f4
rtf-objdata-decoded RTF \objdata at offset 0x1386 1723 bytes