Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a036dfee9911f565…

MALICIOUS

RTF / .DOC

1.89 MB First seen: 2022-10-28
MD5: 244d3b61e174a11c3ed3ea93cd3d6932 SHA-1: b265891db2fe090735d72e42f4e422734a79f5c3 SHA-256: a036dfee9911f565adb5af9221e53dcfc9291398f2d73281abf53e788ee13862
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains an embedded OLE object with decoded Equation Editor payload, strongly indicating exploitation of CVE-2017-11882. The excessive hex data and high-entropy artifact suggest a hidden malicious executable. The file's structure and heuristic firings point towards a classic exploit delivery mechanism.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Decoded Equation Editor payload + PE critical RTF_EQUATION_EDITOR
    RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1982KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000006e.bin
4ab8c311af55a995004fd9905e2198b8225ebc9116d7934a0128cbaca3fc9650
rtf-objdata-decoded RTF \objdata at offset 0x6E 991234 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.