Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 492ea8b208ed5163…

MALICIOUS

RTF / .DOC

1.02 MB First seen: 2023-02-20
MD5: 10f81f6895ce58821af23f9701874e3b SHA-1: 24b02f36190e408c3dfcf42b78da4fef13738e8b SHA-256: 492ea8b208ed5163bcf11754cbb8cae5cd7bb4b9e6b2556129d8b9e371b75c1b
222 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object with decoded Equation Editor payload, strongly indicating exploitation of CVE-2017-11882. The presence of a PE file within the OLE object suggests it's a dropper for a secondary malicious payload. The high entropy and large size of the embedded data further support the presence of an obfuscated or packed payload.

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 ~1073KB 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_off00000073.bin
7d8269481702afb9174c2d8973e37afb99c93b791a46cb2f13cd0f8d40c2e245
rtf-objdata-decoded RTF \objdata at offset 0x73 536732 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.