Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a8bf734d6799d56f…

MALICIOUS

RTF / .DOC

19.5 KB
MD5: fdcd91aa7b0e3bbb23a28209c358d9e8 SHA-1: 71b06082b07c0558d3b350f4c0cba40570eab930 SHA-256: a8bf734d6799d56f61bb58aa044f44bd6b435550600d903f264bb0876a8b627b
180 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects, specifically triggering 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 ` tf_objupdate` directive forces the activation of the embedded object, 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_off0000054f.bin
4378e6b982e6fb3c012217e6d6b5fea9718983a0554efc5bde7c19da5585df01		 rtf-objdata-decoded RTF \objdata at offset 0x54F 1757 bytes

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