Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 194abfeb6f78221b…

MALICIOUS

RTF / .DOC

8.9 KB
MD5: f343ce75606d600a978f4593ad92a5ed SHA-1: 0aca94dd295f12f4deb4505a3f3dd470a7a59752 SHA-256: 194abfeb6f78221b43aff1da8d0aceead6282979840d9aa43bfc20d190ba0ddd
180 Risk Score

Malware Insights

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

The sample is an RTF document that contains embedded OLE object data, specifically triggering heuristics related to the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to allow for arbitrary code execution. The presence of ` tfobjupdate` further indicates an attempt to force OLE activation. Given these indicators, the most likely attack pattern is exploitation of this vulnerability to deliver a secondary payload, commonly seen in spearphishing attachments.

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_off0000115e.bin
47ac6de331fa78d421d9458d78463d15b202b9fe7748088a52b677c475ad6bd5		 rtf-objdata-decoded RTF \objdata at offset 0x115E 1701 bytes

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