Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 ff771beb15df957f…

MALICIOUS

RTF / .DOC

4.1 KB
MD5: e0505131c97d7f3f888dc32647c6221b SHA-1: 6f8250c7693177f2f9a35caafa6d7d3c14deea32 SHA-256: ff771beb15df957f177bba36086ad5563c0805cf7387f716ee6dca6a5f27bfdf
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known Microsoft Office vulnerability. The extasciitilde{}objupdate directive forces the OLE object to activate, leading to arbitrary code execution.

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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000a2.bin
bdd36df5cbd8826e8ae9f46b1d967e69024cb211efb1206863212cf27424497e		 rtf-objdata-decoded RTF \objdata at offset 0xA2 1826 bytes

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