Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 6f944e72dec617c9…

MALICIOUS

RTF / .DOC

1.41 MB First seen: 2023-02-22
MD5: 18ff6de6ae9d7e5caa39a4ff06dec3d6 SHA-1: 4a0ae0d421fcf1a4e60359344a7134056df294f7 SHA-256: 6f944e72dec617c9db58ac01f4f1f5a59add10b19daaf1a46fbb31c115ae16d5
222 Risk Score

Malware Insights

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

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 acts as a dropper for a secondary malicious executable. The high entropy and large size of the embedded data further support the presence of a hidden 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 ~1474KB 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_off0000007d.bin
43eba2f02a4a2723d42f0f6aaa5a6496f06f83632801219e34d60679787ab251
rtf-objdata-decoded RTF \objdata at offset 0x7D 737375 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.