Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8044d7d95ad81969…

MALICIOUS

RTF / .DOC

10.6 KB First seen: 2022-10-10
MD5: b14c7b49f1e76adc0d3f6f1f0f0bd99c SHA-1: b721d1bba2f98227cda4cb19e1930abf117e431f SHA-256: 8044d7d95ad81969d9071fe022b05ba4ae4f5d6e6f2c9e3689c8330ba7d55296
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 Visual Basic T1204.002 Malicious File

The file is an RTF document containing an OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The presence of `equaTion.3` as the class name strongly indicates this exploit. The document also contains a lure instructing the user to 'Enable editing', a common tactic to bypass macro security. The exploit is designed to execute arbitrary code, likely for downloading and running 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_off00000cf4.bin
ba8e92930cb67004c12f87637dfcdcf76a8f043f85235665e80bc2212c5d5b55		 rtf-objdata-decoded RTF \objdata at offset 0xCF4 2110 bytes

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