Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 37157b23b81a70f2…

MALICIOUS

RTF / .DOC

1.12 MB First seen: 2023-03-15
MD5: 5179087fba72025b1aae5d9e588ba50a SHA-1: 5fbe8a15e95afb57e19a99efcbcd39d4fa4ccd58 SHA-256: 37157b23b81a70f2a03f0c22f54fcc2ab6c2b2b7ddca6dada6a95ba1fa49945b
102 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1027 Obfuscated Files or Information

The RTF file contains a large OLE object with excessive hex-encoded data, strongly indicating the presence of a hidden payload. The \objupdate directive suggests an attempt to automatically activate this embedded object upon opening. While no specific family is identified, the structure points to a delivery mechanism for a secondary malicious artifact.

Heuristics 4

  • \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 ~1169KB 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_off00000090.bin
f9b1f84abca11ec23e65811104ec5fe320893e0070455db93bdcc5291f2969ef
rtf-objdata-decoded RTF \objdata at offset 0x90 584648 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.