Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 72461853ff5181bc…

MALICIOUS

RTF / .DOC

1.16 MB First seen: 2023-08-21
MD5: 873022c9b96cc23af24246e96e9b82cd SHA-1: 4ced8384a125239ade93fdcef158d472d88a29e8 SHA-256: 72461853ff5181bc2f91d8b142e4f8da46edb81ed23c4a077c806b76e73e0a80
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 OLE object with decoded Equation Editor payload, strongly indicating exploitation of CVE-2017-11882. The presence of a large, high-entropy embedded artifact suggests it is a packed or obfuscated second-stage payload. The file's structure and heuristic firings point to a classic exploit document 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 ~1216KB 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_off0000008e.bin
133f3eea6b6f75c7a988c1d5db2991583afb9e07d396daa585f369755972eab8
rtf-objdata-decoded RTF \objdata at offset 0x8E 608448 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.