Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 daa8211e4c7fb9ff…

MALICIOUS

RTF / .DOC

1.48 MB First seen: 2023-03-01
MD5: 01831eeeb98963dbf49acbd5de9fd986 SHA-1: b486ebb7160076de8527d754d9de590af96e3c92 SHA-256: daa8211e4c7fb9ffa9fc3346f6ec104c2967a00bf976684b62b229f0df9a6115
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 exploitation of CVE-2017-11882, which is a known vulnerability used to execute arbitrary code. The excessive hex data and high-entropy artifact suggest the embedding of a secondary payload, likely malicious.

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 ~1554KB 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_off00000078.bin
360d282a3bc346951667363d51cb99d8211aa150324f40f9eddc3b96deba97d6
rtf-objdata-decoded RTF \objdata at offset 0x78 777580 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.