Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 0e9b243b8d35f7d3…

MALICIOUS

RTF / .DOC

43.2 KB First seen: 2023-02-21
MD5: c97c74573f79a2623140f9bdff4571fb SHA-1: 9bfbedbab4faae92bce8cff934f1bb5056a4bb54 SHA-256: 0e9b243b8d35f7d34f952625dc851d9f8a4001bfbb0d0b5e604390469335ebbd
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body contains a lure related to marketing strategy, instructing the user to 'Enable editing', which is a common technique to bypass macro security. The critical heuristic firing for CVE_2017_11882_ACTIVATION_RELATED strongly indicates exploitation of this known vulnerability.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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_off000047b8.bin
314f824affa1991819e527129c59cb299a2df8d13339b85cf72e9d593b580083		 rtf-objdata-decoded RTF \objdata at offset 0x47B8 1902 bytes

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