Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 6fe27d5f2bfaabc9…

MALICIOUS

RTF / .DOC

1.82 MB
MD5: e910c50c6ceff600b72571efb67e1165 SHA-1: 6940ce2a4c7eb09dfaac297f320341c1dea8f3d2 SHA-256: 6fe27d5f2bfaabc902e9938356858d6b00a84b38fe0f7be3ebb01b065b999062
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE object data, specifically related to Microsoft Equation Editor, which is indicative of exploitation for client execution via CVE-2017-11882. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_RELATED` heuristics strongly suggests this attack vector. The `RTF_OBJUPDATE` heuristic indicates that the OLE object is forced to activate, likely triggering the exploit. The large amount of hex-encoded data within `RTF_EXCESSIVE_HEX` further supports the hiding of a malicious payload.

Heuristics 5

  • 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.
  • 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.
  • \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 ~1896KB 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001d3c.bin
622a124f2c46308720d79e4871fc46f3ea29c767b5990eda3248ad98735c5aa4		 rtf-objdata-decoded RTF \objdata at offset 0x1D3C 948380 bytes

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