Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8c5a756a70f1bd04…

MALICIOUS

RTF / .DOC

1.64 MB
MD5: 3d9388add4eb1436a441f7f2695600cd SHA-1: 0052d2d4b4a96fc7feb893c3353f3e1d023bb71e SHA-256: 8c5a756a70f1bd048e4cce1e7709265f8dd8739fe1490441020e26b01a5fa51d
240 Risk Score

Malware Insights

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

The RTF document contains multiple indicators of malicious intent, including embedded OLE objects and specific triggers for the Equation Editor vulnerability (CVE-2017-11882). The presence of a large, hex-encoded OLE object strongly suggests it is used to hide and deliver a secondary payload. The critical heuristic firings directly point to the exploitation of CVE-2017-11882, a known vulnerability used for arbitrary code execution.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact 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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1719KB of hex-encoded data inside \objdata sections — may hide a payload
  • 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_off000011ef.bin
8618e647d948c950a1000ce9e6efa4f55453cc5a67b92e42951c79cd76db8d25		 rtf-objdata-decoded RTF \objdata at offset 0x11EF 860033 bytes

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