Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 88d6f042585c2e12…

MALICIOUS

RTF / .DOC

1.63 MB
MD5: c3f435c1711eb57e13acd2cb1fdf04a2 SHA-1: a4cedd66c27cf1aaed9ebf9fc0deb1f82dc937c3 SHA-256: 88d6f042585c2e129d891c4bb6217544c7d8cc2a814d4bb61cd7359165e4af84
220 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data, specifically related to Microsoft Equation Editor. Critical heuristics indicate the presence of a payload associated with CVE-2017-11882, a known vulnerability in Equation Editor. The ".bin" file extracted from the objdata section is likely the second-stage payload, although its specific function cannot be determined from static analysis alone. The presence of ".objdata" and ".objupdate" sections further supports the exploitation of OLE object handling within the RTF document.

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 ~1705KB 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_off0000160a.bin
846d51bb4f4b55a266770356a64f992276e48ec000150ed7979936418b3e9895		 rtf-objdata-decoded RTF \objdata at offset 0x160A 852890 bytes

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