Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 856cf421c68a4123…

MALICIOUS

RTF / .DOC

3.5 KB First seen: 2022-03-29
MD5: 8fbc946e4281e310123f6f065cf8db4e SHA-1: dd86d9897f1e49468d38bef981d0453accd5b73d SHA-256: 856cf421c68a412371fbf6167cb5c0c4d3c5ff7ea3a49625b2c1646f4b7bef04
121 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data, specifically triggering the Equation Editor vulnerability. The \objupdate directive forces the activation of this embedded object, leading to arbitrary code execution. This is a common technique for delivering malicious payloads via weaponized documents.

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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000a4.bin
9b49c916b7e790b1dc37a2d018269a7e45407375152d20a58436bf4352a52100
rtf-objdata-decoded RTF \objdata at offset 0xA4 1586 bytes