Malicious RTF — malware analysis report

Static analysis result for SHA-256 f63a9a50113ba633…

MALICIOUS

RTF

42.9 KB
MD5: b5b56914cbe7ebaaabb85b54942e42ac SHA-1: 906253e90155df8ff78f853abe8a13c47ffe0e24 SHA-256: f63a9a50113ba633bc752bee1f9a690eb074753757db02c7f1115aafdc3e0ddd
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates this exploit. The ` tf_objupdate` heuristic suggests that the embedded object is configured to activate automatically, leading to client-side code execution. No specific family could be identified, but the exploit vector is clear.

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_off00000d20.bin
82080fcbdca28dcbac184eaf1628a9cb6a776d8cdf4e800de1617646f2f38dbc		 rtf-objdata-decoded RTF \objdata at offset 0xD20 1852 bytes

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