Malicious RTF — malware analysis report

Static analysis result for SHA-256 a66d36150aec38fc…

MALICIOUS

RTF

1.60 MB First seen: 2022-05-17
MD5: 5c920b8c296f8551a5770059cd45e068 SHA-1: ec3436ff44d7f26f0469a317542e13d73908eba2 SHA-256: a66d36150aec38fcc538b871e4dbf2065f050a188cb82dccc9bdff671229bf41
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The critical heuristic firing confirms this, indicating that the object is designed to be activated and execute arbitrary code. The embedded OLE object likely contains a script or executable designed to download and run a second-stage payload. The presence of 'Equation.3' as the class further solidifies the exploitation vector.

Heuristics 5

  • 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.
  • 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.
  • 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_off000012ab.bin
4117ceac4f076b260f6b504396cf7b77a4d8604cd75f146496eb713c18880898		 rtf-objdata-decoded RTF \objdata at offset 0x12AB 86085 bytes
objdata_01_off00036ca4.bin
dc3e57eb4562938037bc9ba4c97a11787e9fc2419e976a064cfb40e3396c9e40		 rtf-objdata-decoded RTF \objdata at offset 0x36CA4 345132 bytes

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