Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 17d36d448455ca6a…

MALICIOUS

RTF / .DOC

1.50 MB First seen: 2023-09-15
MD5: afc6933b034f5a27970889717ddbb8ee SHA-1: 761f25ec8b340ce1da12f64a03472b935f805c7d SHA-256: 17d36d448455ca6a292f327a84435d646ffaf4b574a2faa77884db62c5b756f3
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains OLE object data, specifically a decoded Equation Editor payload. Heuristics indicate a critical vulnerability, CVE-2017-11882, is being exploited to embed and activate a Portable Executable (PE) file. The excessive hex data and the presence of an OLE1 native payload strongly suggest this is a delivery mechanism for a secondary malicious artifact.

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 ~1574KB 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_off00000098.bin
f3da945c007abbc18118d9850dacf46ce31ce97c14a322d47c1c09cd0a6f70c2
rtf-objdata-decoded RTF \objdata at offset 0x98 787288 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.