Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 ae554c838c7389ca…

MALICIOUS

RTF / .DOC

2.48 MB First seen: 2022-08-11
MD5: 0a03c724d8f793c7019d232cfdc8e6d4 SHA-1: 0dc97e5825bdb91a03629815372916bfe641e218 SHA-256: ae554c838c7389ca65c3b7f5abce1006217c9893316e1e65fc22791ee335051f
380 Risk Score

Malware Insights

MITRE ATT&CK
T1027 Obfuscated Files or Information

The RTF document contains embedded OLE objects and utilizes the Equation Editor vulnerability (CVE-2017-11882) to execute arbitrary code. The presence of a PE header within the hex-encoded data strongly suggests that a malicious executable payload is being dropped and executed. The ClamAV detection as Rtf.Dropper.Agent-9965975-1 further confirms its dropper functionality.

Heuristics 9

  • 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 ~1637KB 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001291.bin
d08254b4649eaa24e9b5ce77519de10265f2c8548b21605d1a8a7196a6a70d72		 rtf-objdata-decoded RTF \objdata at offset 0x1291 824645 bytes
objdata_01_off00199e8c.bin
ffd8c2482cc64da211bcb7ca32c7331bf3796ad5ca2159f697062f334496c915		 rtf-objdata-decoded RTF \objdata at offset 0x199E8C 187349 bytes

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