Malicious RTF — malware analysis report

Static analysis result for SHA-256 90fb2b064ec4353d…

MALICIOUS

RTF

11.2 KB First seen: 2022-10-11
MD5: 9ebf9dac8f3ecf36d77d3f39d77ee04a SHA-1: 4da2c44aeabbd7f0bff0a04de6e75aa9338af109 SHA-256: 90fb2b064ec4353d02ec3a9d15540cf70dccb7d7a6d10bfe4be8bb73012ab52e
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1559.001 Component Object Model Hijacking T1059.001 PowerShell T1204.002 Malicious File

The file is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body contains a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security settings. The embedded object is designed to activate automatically, likely leading to the execution of a secondary payload.

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_off000014a9.bin
db943b005951ce34200e83752afab5efa3692a34c927f0de89211d37a321c992		 rtf-objdata-decoded RTF \objdata at offset 0x14A9 1758 bytes

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