Malicious RTF — malware analysis report

Static analysis result for SHA-256 5bf47c7a0f1388e5…

MALICIOUS

RTF

27.2 KB First seen: 2022-11-10
MD5: 692900f84ce8e3b5ff5c601b434f199e SHA-1: 9364f0b97b2e30e55855ae278163fd5b82768bf8 SHA-256: 5bf47c7a0f1388e519b303cbcb66f41ac08aa049f52c689c61199b8f759d0278
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic T1204.001 User Execution: Malicious Link

The RTF document contains an embedded OLE object specifically identified as related to CVE-2017-11882, exploiting the Equation Editor vulnerability. The document also includes a lure instructing the user to 'Enable editing', a common tactic to bypass security measures and trigger the exploit. The embedded object's class name 'eqUatioN.3' is a strong indicator of this specific vulnerability.

Heuristics 6

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 1 \objdata section(s) — embedded OLE objects
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000521f.bin
5b6c701056c6e7e4ca595cb49299d47516d0eeb85b86d090935db6a902db5a02		 rtf-objdata-decoded RTF \objdata at offset 0x521F 1919 bytes

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