Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 033aed8c2418343a…

MALICIOUS

RTF / .DOC

1.75 MB
MD5: e8c974b2b5a7126845c9c5640dfcfe75 SHA-1: 1e05173b4f88fea133bf98419c8eaf4ff021eb29 SHA-256: 033aed8c2418343a8e318d5d988a7fc902fcc1123b7e06d32a7eab0e55f7ab29
260 Risk Score

Malware Insights

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

The sample is an RTF document containing OLE objects, specifically related to CVE-2017-11882, which is a known vulnerability in Microsoft Equation Editor. This vulnerability is leveraged to execute a second-stage payload, likely a binary, as indicated by the large amount of hex-encoded data and the presence of an MZ header within the decoded OLE object. The document itself does not contain readable content, suggesting its primary purpose is exploitation.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 ~1824KB 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_off000000a3.bin
4455b7b854bc30f0430cb1041510c964c01233ff7e7201e472bed0f73c9e3efc		 rtf-objdata-decoded RTF \objdata at offset 0xA3 913541 bytes

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