Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c0a2ece177e5c314…

MALICIOUS

RTF / .DOC

1.68 MB First seen: 2023-03-06
MD5: fc44a620ec056045e83655cc827f1823 SHA-1: fafbee1b0ff5c313b9f86e85a417cbfb7e34abcc SHA-256: c0a2ece177e5c314d2c00a40f9ade9000080506440f8b7a8caebe42b552da064
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. Critical heuristics indicate a relationship with CVE-2017-11882, suggesting the file exploits this vulnerability to embed and execute a Portable Executable (PE) file. The presence of excessive hex-encoded data further supports the hiding of a malicious 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 ~1759KB 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_off00000074.bin
caa182869edca1b91c11f465e0d002556006a783895f928beffb5e3ecef7a245
rtf-objdata-decoded RTF \objdata at offset 0x74 879824 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.