Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 54240271ba86cd35…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-15
MD5: 2dd6da56d2b157365a51fb76764db9ed SHA-1: 51bb9de33d70e0522ddc5c6183c298a58fe02500 SHA-256: 54240271ba86cd35518902f260f010583dc0a88ed3f304de9136295375614eb8
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to achieve code execution. The embedded OLE object and specific heuristic firings strongly indicate this exploit. The decoded object data contains obfuscated VBA-like code that appears to be designed to execute further payloads, though the full script could not be reconstructed due to truncation.

Heuristics 5

  • 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.
  • \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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001347.bin
deee85d71283f827c3bd651c0c7a839058fc5c34e423d0a374eb1e0b8b91a1d1		 rtf-objdata-decoded RTF \objdata at offset 0x1347 25602 bytes
objdata_01_off00019556.bin
689965aaaf88dfda2c46136e8ee45ccbdf5d380abcba88d5f9ff529d3c59ced2		 rtf-objdata-decoded RTF \objdata at offset 0x19556 463381 bytes

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