Malicious RTF — malware analysis report

Static analysis result for SHA-256 59033cc4f75f3d68…

MALICIOUS

RTF

1.82 MB First seen: 2023-09-28
MD5: f0ef2c3a320448b3a8ea0535da3b411b SHA-1: 46816ee3fbf52cc2a4e5b12be672801f01df1fb6 SHA-256: 59033cc4f75f3d68650b5956cc2cdf570560084545a6db1ff3c675411691c71f
222 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link 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 related to CVE-2017-11882, suggesting the document is designed to exploit this vulnerability upon opening. The excessive hex data and high-entropy carved artifact further support the presence of a hidden malicious payload, likely a second-stage 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 ~1910KB 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_off0000008c.bin
356bffb88cf70bb6232c21334de8de60e36d9ace6becd1d323b5a8beb3d05526
rtf-objdata-decoded RTF \objdata at offset 0x8C 955266 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.