Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f3291a66595f3be8…

MALICIOUS

RTF / .DOC

25.1 KB First seen: 2022-11-16
MD5: 3cd7a06a31840158b726504607ae60c0 SHA-1: 9ddb4886ae06a75898e489895fa9c9fd2660894e SHA-256: f3291a66595f3be8df6b67ba8285c0fda2c5db2ecd8fbf4273e9fa1d118c5334
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 PowerShell

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The presence of OLE object data and specific Equation Editor ProgIDs strongly indicates exploitation of this known vulnerability. The document also contains a lure to enable editing, a common tactic for macro-based malware delivery. The primary goal is likely to execute a secondary payload via the exploited 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_off00004bb8.bin
8af88f076a2cfcac701c1cdcb7f1b8992eb85ef13767286ec2c09625726fd626		 rtf-objdata-decoded RTF \objdata at offset 0x4BB8 1401 bytes

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