Malicious RTF — malware analysis report

Static analysis result for SHA-256 3eaaf3f5f60aa2c1…

MALICIOUS

RTF

1.72 MB
MD5: 88498661ad970b7faad7a3d99a0e9195 SHA-1: 13d772e677b646e5420f509ba2ae42329fe244c4 SHA-256: 3eaaf3f5f60aa2c147141f154fab64d129c5f43226372c7dc6a2f5b48e6555b4
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains multiple critical heuristic firings indicating the exploitation of CVE-2017-11882 via an embedded Equation Editor OLE object. The presence of large amounts of hex-encoded data within objdata sections suggests a hidden payload. The RTF_OBJUPDATE heuristic further indicates that the OLE object is designed to be activated automatically. While no specific family could be identified, the exploit vector is clear.

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 ~1793KB 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_off00001732.bin
e7dc89c09639752748119968bc06d2dd58d2d368d98472e75e5d7d07037e0a05		 rtf-objdata-decoded RTF \objdata at offset 0x1732 896562 bytes

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