Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7c7aac8a06207bdc…

MALICIOUS

RTF / .DOC

1.86 MB
MD5: bb47d860a33bd8cf0fb5d895b477dac2 SHA-1: 9a694eed5aa25571bd7714492762e6f0be2ac4d7 SHA-256: 7c7aac8a06207bdc4f59cda2ec034f6c1dc31a2b6dcd33372e3266cfb6181821
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1559.001 Component Object Model

The sample is an RTF document containing an OLE object that leverages the CVE-2017-11882 vulnerability in Equation Editor. This vulnerability allows for arbitrary code execution when the OLE object is activated. The large amount of hex-encoded data within the object data section is indicative of a hidden 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 ~1947KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003d.bin
ce7e002b44b70c9aae752f344d8787ae0ea1d15feb628e6b1927180a1e165a14		 rtf-objdata-decoded RTF \objdata at offset 0x3D 973750 bytes

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