Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c622addb85838ffa…

MALICIOUS

RTF / .DOC

27.7 KB First seen: 2023-01-27
MD5: c0b310b5c594ee858912a67401ca2ad5 SHA-1: 50e8178ca2a2643e79854a222bcf946ca75e2d79 SHA-256: c622addb85838ffa54de940122848408c0cf804eb5b4ec61c8526b94704472b4
140 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1059.005 Visual Basic

The sample is an RTF document containing an embedded OLE object that exploits the Microsoft Equation Editor vulnerability. The document body contains a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security settings. The presence of RTF_OBJDATA, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly suggests an exploit targeting the Equation Editor to deliver 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_off000051de.bin
2d219eedf54f8fc2c3a00f2821e399e57fbe5b0b655843d8556624659abadf61
rtf-objdata-decoded RTF \objdata at offset 0x51DE 1659 bytes