Malicious RTF — malware analysis report

Static analysis result for SHA-256 6dfdebc98dc7c591…

MALICIOUS

RTF

1.60 MB
MD5: ae0cdbe7a34cdbacd9f306c84cadee53 SHA-1: 18a85ea7d5bc9f105b44a764856768e8dac517d5 SHA-256: 6dfdebc98dc7c59153bdb12ef95fc2cb9411ca0428481ae3dcfce02ee8039477
180 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability related to Equation Editor. This exploit allows for the execution of arbitrary code, likely to download and run a secondary payload. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this exploit vector.

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_off000011e1.bin
f8d577f9700604fc26ab63f059e12bacb030221c296a3aacbb7ad42188d89935		 rtf-objdata-decoded RTF \objdata at offset 0x11E1 55961 bytes
objdata_01_off000333db.bin
078f4826f1fd7ea74b366f8203fc5dc103f9012dddd7cede4b9d1d69bc7eed6c		 rtf-objdata-decoded RTF \objdata at offset 0x333DB 351910 bytes

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