Malicious RTF — malware analysis report

Static analysis result for SHA-256 caa7719f6020d911…

MALICIOUS

RTF

11.7 KB First seen: 2023-03-08
MD5: 53b7ecf8450a8d221651aafd0a799b05 SHA-1: cb563241140c9f2dc9842fa777bfe3affcab639a SHA-256: caa7719f6020d911cc3e6ad542331508e22180445d7fa9206bf60193cb69d5e9
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1027 Obfuscated Files or Information

The RTF document contains an embedded OLE object that is specifically targeted by the CVE-2017-11882 vulnerability. The `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics confirm this exploit attempt. The `RTF_OBJUPDATE` heuristic indicates that the OLE object is forced to activate, leading to the execution of the embedded malicious content.

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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000d4a.bin
d87fd6e6e77791198da3ca80623f357ab9d41c9e60c868e2703a2630fd85d997		 rtf-objdata-decoded RTF \objdata at offset 0xD4A 1854 bytes

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