Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b180684c84bffe54…

MALICIOUS

RTF / .DOC

30.3 KB First seen: 2023-01-27
MD5: 6be1566bdd359b3e118fe705ce223dee SHA-1: ca1d12ec7caaf4067f828dc8eb38df79bc93fa69 SHA-256: b180684c84bffe54e468e3a7870e2cfd45952b21de40aaa9c5165c4c30626192
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in the Microsoft Equation Editor. The 'SE_ENABLE_LURE' heuristic indicates the document prompts the user to enable editing, a common tactic for malware droppers. The presence of OLE object data and specific Equation Editor-related firings strongly suggest exploitation of this known vulnerability to deliver a 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_off000056de.bin
508a5dcd1ee112a02eeb9f2e484beb51286d7a397d85cbd4c00bbf9f5e6c6ddd		 rtf-objdata-decoded RTF \objdata at offset 0x56DE 1924 bytes

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