Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f62618b888bd1d30…

MALICIOUS

RTF / .DOC

44.4 KB First seen: 2023-02-20
MD5: 504b9101a5a633de932a5a2c8f5b302f SHA-1: 1cc81c681824263032f88652b82ff73821ebbdb4 SHA-256: f62618b888bd1d305f278cdb50711f85a53f2101ba44067408a647682fd3fee7
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document that contains an embedded OLE object, specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_OBJAUTLINK and RTF_EQUATION_EDITOR heuristics strongly indicates exploitation of this known vulnerability. The SE_ENABLE_LURE heuristic suggests the document prompts the user to enable editing, a common social engineering tactic to bypass security measures. The embedded OLE object is likely a secondary payload designed to be executed upon successful exploitation.

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_off00004bc5.bin
3720ae9cfe89cfa5fcf750f321ae35b2b7e0d73ec3774c892b62e60a9aed7320		 rtf-objdata-decoded RTF \objdata at offset 0x4BC5 2011 bytes

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