Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f81892a32603378e…

MALICIOUS

RTF / .DOC

29.5 KB
MD5: cbdcabe7b5e2660d05bf06c76dca4f33 SHA-1: cd00cfb42f7aad865ae8803558a81f391955331d SHA-256: f81892a32603378ea548812e51a52825d08c2275fc3c7a0f1e2b00098cb1a6cc
120 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The sample is an RTF document that contains OLE object data and triggers an objupdate event, indicating it attempts to activate embedded objects. The critical heuristic firing for RTF_EQUATION_EDITOR strongly suggests exploitation of the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for remote code execution, which is likely used here to download and execute a secondary payload. No specific family could be identified, but the exploitation method is clear.

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_off00001719.bin
63b20058dbf421ea51a1baeaef5f9a3963089ab60969d5bbc0fabeba9800d793
rtf-objdata-decoded RTF \objdata at offset 0x1719 1585 bytes