Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c81b8399e6dcd40a…

MALICIOUS

RTF / .DOC

23.0 KB First seen: 2022-11-10
MD5: aee6c7fb59b87c8f776cb1092ac48402 SHA-1: 5e7bae25edee5e9c032e53fc81e68c20bd4aa848 SHA-256: c81b8399e6dcd40a67887471b6b265d170f3fc75079875c4c53d521f92a3969c
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The RTF document contains an embedded OLE object with a split Equation Editor ProgID, indicating an attempt to exploit the Equation Editor vulnerability (CVE-2017-11882). The ".objupdate" directive forces OLE activation, and the document includes a lure to "Enable editing" to bypass security settings. This combination strongly suggests the file is a dropper designed to exploit this vulnerability to download and execute a secondary payload.

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_off00004535.bin
3b76d8d82893fbfb26e16868cacdd9b6b4d1ed3177d5ad8a6626d6bea5c8be09
rtf-objdata-decoded RTF \objdata at offset 0x4535 1633 bytes