Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 3bb225609921fc8a…

MALICIOUS

RTF / .DOC

1.38 MB First seen: 2023-02-22
MD5: dd765b59cacb9d97b69624315dfba7f3 SHA-1: 19c5e16cd8d0041cb067eeda785ebd4042c390fd SHA-256: 3bb225609921fc8a6f81296bb1b6a03ec7441babff46560ab365cfdffa954626
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to deliver a malicious payload. The presence of OLE object data and a decoded Equation Editor payload strongly indicates exploitation of this known vulnerability. The excessive hex data likely hides the embedded 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 ~1445KB 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_off00000075.bin
7f8090b58d91c100e8127f7f05d8639ef5a167903193a3cfa1675695acda5d04
rtf-objdata-decoded RTF \objdata at offset 0x75 722981 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.