Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 ea1ac8040f307cab…

MALICIOUS

RTF / .DOC

1.59 MB
MD5: ed18f902ac9db5df0d922df455fd820a SHA-1: 039f673876ba03c678a2285e209b5b944b7ed7d4 SHA-256: ea1ac8040f307caba810a029c41a3191f1656aa9538ad25f154e4a2b668fb624
220 Risk Score

Malware Insights

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

The RTF document contains OLE object data, specifically identified as related to CVE-2017-11882. The presence of ".objdata" sections and the "RTF_EQUATION_EDITOR" heuristic strongly indicate the exploitation of this vulnerability. The "RTF_OBJUPDATE" heuristic suggests that the OLE object is automatically activated upon opening the document, leading to the execution of the embedded payload. The large amount of hex-encoded data within the OLE object likely hides the secondary payload.

Heuristics 5

  • 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 ~1671KB 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000d3.bin
20fec2f552c907d7192fa8db3a1e54e166bb3c70e51123f11e494ef3b1937b59		 rtf-objdata-decoded RTF \objdata at offset 0xD3 835687 bytes

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