Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e12084e91783b6b9…

MALICIOUS

RTF / .DOC

26.6 KB First seen: 2022-12-01
MD5: b6297870b78eda093e7421af79ff7de1 SHA-1: 7d61b7850697bd21527abbdcfb3ec919d5dc97cc SHA-256: e12084e91783b6b96678306a0bdf64c62e0a4fe0321db5f708c4a9b78062abe2
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 CVE-2017-11882 vulnerability in Microsoft Equation Editor. The document also contains a lure instructing the user to 'Enable editing', a common tactic to bypass macro security. The exploitation of Equation Editor is the primary mechanism for delivering a secondary 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_off00004a44.bin
1016094edb8cde0973db8ece02c8825a73e0572ad70c4a1278ebb2aca7c0af60		 rtf-objdata-decoded RTF \objdata at offset 0x4A44 1809 bytes

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