Malicious RTF — malware analysis report

Static analysis result for SHA-256 c82826b83e49aa89…

MALICIOUS

RTF

2.9 KB First seen: 2019-03-18
MD5: baee326c5dc49afe08006f7d3c5d23e7 SHA-1: 39c36f5d7d5df5f1675c9a61eb8c171f37bffc52 SHA-256: c82826b83e49aa891ddef787c63e25375577f2be6d08356e37aa092877313b3d
120 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains critical heuristic firings indicating the use of the Equation Editor vulnerability (CVE-2017-11882). The presence of OLE object data and the \objupdate directive strongly suggest that the file is designed to exploit this vulnerability to execute code. This is a common method for delivering secondary payloads, such as malware downloaders.

Heuristics 3

  • Split hex Equation Editor ProgID + OLE object critical CVE likely 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 1451 bytes
SHA-256: 34f3154046eebd18c9984c2de9973f2c5769f9be764acfa84a6291cc3e409036

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