Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a78211f3900b20a8…

MALICIOUS

RTF / .DOC

35.1 KB First seen: 2023-02-10
MD5: 8415d92d4822c94049b4f4a8c7b9979a SHA-1: cd01ec8e9a1426ca8c5effb97bfa429a9ccccc7e SHA-256: a78211f3900b20a8a68a37b4471fbccda92ad3cb17f3a2eddc4f0b998df2feb3
220 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body includes a lure instructing the user to 'Enable editing' to view the content, which is a common technique to bypass macro security settings. The exploitation of CVE-2017-11882 is a critical finding, indicating the document is designed to execute arbitrary code upon activation.

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_off00005078.bin
9b4ba6911a48c95dddf63517ee84cdb37ab4dac9ef8ae2f389394b1d426d50ec		 rtf-objdata-decoded RTF \objdata at offset 0x5078 1442 bytes

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