Malicious RTF — malware analysis report

Static analysis result for SHA-256 0b7921ec4ae1f9cf…

MALICIOUS

RTF

62.9 KB First seen: 2023-07-04
MD5: 5d35087b594778cb1c290e4a48df9a2e SHA-1: 516e599d970cd166efee5d479411312f8c9edd2b SHA-256: 0b7921ec4ae1f9cf807b13ec103b31eda48de48d8b1e9cbbe0fbe03cdbfd2970
120 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Phishing: Spearphishing Attachment T1204.001 User Execution: Malicious Link

The sample is an RTF document that contains an embedded OLE object, specifically targeting the Equation Editor vulnerability. The presence of \objupdate indicates that the embedded object is designed to be activated automatically, likely leading to the download and execution of a secondary payload. The heuristics strongly suggest exploitation of CVE-2017-11882, a known vulnerability in the Equation Editor component.

Heuristics 3

  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001f0c.bin
86d4d3e2f5ad62bf20c75237ce2fd059d31980b9637e156616ddc458956aa12b		 rtf-objdata-decoded RTF \objdata at offset 0x1F0C 17456 bytes

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