Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 42487bd90d60cc3c…

MALICIOUS

RTF / .DOC

11.7 KB First seen: 2022-10-03
MD5: 06e10f3fce4796770b76d377bd7771f6 SHA-1: 1a1a8ebd2069d5eb6398d3aaca4664355d97ffb9 SHA-256: 42487bd90d60cc3c61a5af0a126f8e2e4a855e680099d1a6fda96eb658645026
220 Risk Score

Malware Insights

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

The file is an RTF document containing a malicious OLE object, specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_OBJDATA, RTF_OBJAUTLINK, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known vulnerability. The SE_ENABLE_LURE heuristic suggests the document also employs social engineering to trick the user into enabling content. The primary attack vector is likely the exploitation of the Equation Editor to achieve code execution, leading to the download and execution of a further stage.

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_off00000b51.bin
6b81275ca3387eef22060979f1050db62cde2e7bdc473c6107efcc603130cc50		 rtf-objdata-decoded RTF \objdata at offset 0xB51 1635 bytes

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