Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 51f03249df321a5c…

MALICIOUS

RTF / .DOC

1.04 MB First seen: 2022-08-30
MD5: 7b5b2726ccab4e89353e0fd0dbc3fec3 SHA-1: ab4b840f78391214675d90ad42b8b9916dabd451 SHA-256: 51f03249df321a5c723fc17c78e3dd9620108b49eb4dc64b6604cf5d52545794
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) through embedded OLE objects. The critical heuristic firing for RTF_EQUATION_EDITOR and the related CVE_2017_11882_ACTIVATION_RELATED heuristic strongly indicate this exploit. The embedded OLE object is likely designed to download and execute a secondary payload.

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_off000012b8.bin
6ced001a9c47a003d4ff63c1b010bb11161b5f82ae5d4ae3de62af9ce4a1edbe		 rtf-objdata-decoded RTF \objdata at offset 0x12B8 73186 bytes
objdata_01_off0002b014.bin
e1fc1a4c0e67e69e3fb71023b7446271b7980a05bfadf3f1c66142aaf4530e1c		 rtf-objdata-decoded RTF \objdata at offset 0x2B014 187172 bytes

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