Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 57f41af400d3ff48…

MALICIOUS

RTF / .DOC

1.55 MB First seen: 2023-09-13
MD5: d78de46faa7d94c7eafbb0ddfc235716 SHA-1: 27a2f5d27b3ac0349e1b1fe17b97b7f03512b915 SHA-256: 57f41af400d3ff4847b3d8b84098795a5f41dcceb1fc202662b393e1dee07bed
222 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for arbitrary code execution when the object is activated. The decoded object contains a PE file, indicating it's a payload delivery mechanism. The high entropy and large size of the hex-encoded data further suggest it's hiding a malicious executable.

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 ~1620KB 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
c7df5b79d103563d3c0f530bc0ed13f96e30261c2d17f6647f10990316f9af48
rtf-objdata-decoded RTF \objdata at offset 0x8E 810279 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.