Malicious RTF — malware analysis report

Static analysis result for SHA-256 3c5ab56bd9dfd136…

MALICIOUS

RTF

2.54 MB First seen: 2022-08-09
MD5: 15b7675ce97dcabf8a7e56eaa445fd0e SHA-1: eddfebe9e1d1a3b43d593e088569e68a286f0565 SHA-256: 3c5ab56bd9dfd136c968bc901740a4350adb154ddd75e009735ad14b0ae949e4
382 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1204.002 Malicious File

The RTF document contains multiple indicators of exploitation for CVE-2017-11882, including OLE object data, split Equation Editor ProgIDs, and composite monikers. The presence of a PE header within the hex-encoded object data strongly suggests that the embedded OLE object is a malicious executable payload. ClamAV also detected this file as Rtf.Dropper.Agent-9965975-1, further confirming its malicious nature as a dropper.

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 ~1705KB 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_off00001277.bin
cacad3dbf6204e174030471d67d1ee19d88b5d5bcfd3d1536266b73bf791ecb9
rtf-objdata-decoded RTF \objdata at offset 0x1277 858437 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.46, consistent with packed or encrypted content.
objdata_01_off001aa658.bin
ffd8c2482cc64da211bcb7ca32c7331bf3796ad5ca2159f697062f334496c915
rtf-objdata-decoded RTF \objdata at offset 0x1AA658 187349 bytes