Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a7b8ed29675fe0f8…

MALICIOUS

RTF / .DOC

20.3 KB
MD5: cb3a5fea2bb9a4a8b09eb97ec192aefa SHA-1: 724824cae8fbdf1c9371989e172982f21c908699 SHA-256: a7b8ed29675fe0f87f13b799f3643c69ae777574a467464f0bd4779709963166
180 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that leverages the Equation Editor. Heuristics indicate a critical firing for RTF_EQUATION_EDITOR and high firings for CVE_2017_11882_ACTIVATION_RELATED and RTF_OBJUPDATE, strongly suggesting exploitation of CVE-2017-11882. This vulnerability allows for arbitrary code execution when the embedded object is activated, likely leading to the download and execution of a second-stage payload.

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_off000014cc.bin
3de31e78283f5a84aeec6dd7c7dc4750b33c6a5fec29f53a3a1cd04070eb7ea2		 rtf-objdata-decoded RTF \objdata at offset 0x14CC 1488 bytes

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