Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e654a4249f4f722b…

MALICIOUS

RTF / .DOC

1.56 MB First seen: 2022-02-18
MD5: b4ce17002884d0e18e0d590ce1e19337 SHA-1: ed1690e76d4db4b76dc9c8e011af2d1545028183 SHA-256: e654a4249f4f722be213e58fee121347665eb1a6cf34e55a455c17e917599137
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.001 Malicious Link T1059.001 PowerShell T1204.002 Malicious File

The file is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) via an embedded OLE object. The heuristic firings indicate the presence of OLE object data and specific indicators related to the Equation Editor exploit. The large amount of hex-encoded data within the OLE object suggests it is used to hide a payload. The attack pattern is consistent with exploiting this known vulnerability to execute arbitrary code.

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 ~1635KB 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_off0000003e.bin
2a616b356d49bfc363abe04f9aa307733e22e4ab9e20e8546e5e7334af1523c4		 rtf-objdata-decoded RTF \objdata at offset 0x3E 817820 bytes

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