Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 4e385e81ff039ec7…

MALICIOUS

RTF / .DOC

1.86 MB First seen: 2022-02-17
MD5: 7e8ccd6c8b870c9eecd97fa43fdd4db9 SHA-1: 4e201701afe101bf68cc1397b5146c89887d9428 SHA-256: 4e385e81ff039ec76d1b273bb30a68fca6dbdce7b27ae13cd1fce135e771045f
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: Malicious File T1559.001 Component Object Model Hijacking: Component Object Model T1059.001 Command and Scripting Interpreter: PowerShell

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_RELATED` heuristics strongly indicates exploitation of this known vulnerability. The `RTF_OBJDATA` and `RTF_EXCESSIVE_HEX` heuristics suggest that a significant payload is hidden within the OLE object data, intended to be executed upon activation.

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 ~1955KB 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003c.bin
562dc354a339a659a67700ad742126aaeb899a4c1310f32d1d8ddc43c07f9703		 rtf-objdata-decoded RTF \objdata at offset 0x3C 977563 bytes

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