Malicious RTF — malware analysis report

Static analysis result for SHA-256 f34256be95f32fb1…

MALICIOUS

RTF

2.54 MB
MD5: 12c52c0df77b64dd32e2a5029043ea95 SHA-1: a00cc1e74c968c938341a276d0595314b07aa50a SHA-256: f34256be95f32fb1f3e382de94347d504c280fa20fca51694cc2a6df7b53be51
220 Risk Score

Malware Insights

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

The RTF file contains critical heuristic firings indicating the exploitation of CVE-2017-11882 via Microsoft Equation Editor. The presence of OLE object data and excessive hex-encoded data strongly suggests that the file is designed to embed and execute a secondary payload. The exploitation of this vulnerability is a common method for initial client execution.

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 ~2653KB 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_off000010c9.bin
f12f8c0794000fbeada6bce5c027d361139f5f494c3312ba860dbd3d1384afcf		 rtf-objdata-decoded RTF \objdata at offset 0x10C9 884828 bytes

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