Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 1e5a998b2e9fbfaf…

MALICIOUS

RTF / .DOC

1.66 MB First seen: 2022-03-02
MD5: 0d831116cd26e8ac9cf09ef879a9098c SHA-1: cdc3885efbf5c908a58e8450ed9f55c906cc24ca SHA-256: 1e5a998b2e9fbfafb683e905d714e674f9f6e7bf3396ae164f4b7b0d43e6dda5
240 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be used to download and execute arbitrary code. The presence of the OLE object and the specific heuristic firings strongly indicate this exploit vector. No specific family could be identified, but the attack pattern is clear.

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 ~1728KB 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_off0000205b.bin
c50f99d0d258d761085f7d60b26110f6f5cf4d8686138e92e242411d5d507b27		 rtf-objdata-decoded RTF \objdata at offset 0x205B 864421 bytes

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