Malicious RTF — malware analysis report

Static analysis result for SHA-256 a64a69cd587f18e1…

MALICIOUS

RTF

2.16 MB
MD5: ed8c9d0f506f43801d64042934b8ab78 SHA-1: 831d22db6178c4307addade8fe61316bfcbe7450 SHA-256: a64a69cd587f18e1733345f0065cf57e4125e697075d7bc0875d12710a338673
220 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data, specifically related to Equation Editor, which is indicative of the CVE-2017-11882 vulnerability. This vulnerability is known to be exploited for client execution, likely to download and run a secondary malicious payload. The presence of a large amount of hex-encoded data within the OLE object further supports the hypothesis 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 ~2266KB 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_off000000a5.bin
f63f6726763efeda644ccd3e4cc7b6a3995c3552d3fb09a5c608cdc56d0bae2c		 rtf-objdata-decoded RTF \objdata at offset 0xA5 906513 bytes

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