Malicious RTF — malware analysis report

Static analysis result for SHA-256 56c5a7b4ee1e03bd…

MALICIOUS

RTF

3.87 MB First seen: 2022-06-16
MD5: 877a549b866f0cb33137d482a312cab6 SHA-1: d52e10f94b004ad1eabd72e9a3448f8bdde58ace SHA-256: 56c5a7b4ee1e03bd11e524b9a5e532aeb44512a395d8aa7ae8b7fa0322e6e4be
382 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1559.001 Component Object Model Hijacking T1059.003 Windows Command Shell T1105 Ingress Tool Transfer

The RTF document contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability through the Equation Editor. This exploit is known to be used for dropping and executing arbitrary code. The presence of a PE header within the hex-encoded object data strongly suggests that a malicious executable payload is being delivered. The ClamAV detection further confirms the malicious nature of the file.

Heuristics 10

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • \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 ~2015KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000012b8.bin
498b6016381b61747e1a3cee661ec6949a4baba4776368eb1f7f03384ed591ce
rtf-objdata-decoded RTF \objdata at offset 0x12B8 1025323 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.88, consistent with packed or encrypted content.
objdata_01_off0020168a.bin
a13335cde7397140c2d0911d9381238c9caf13f5f7932e575fd1b5d0cf687773
rtf-objdata-decoded RTF \objdata at offset 0x20168A 463856 bytes