Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 9f047d077797fef3…

MALICIOUS

RTF / .DOC

1.69 MB
MD5: 55c50bfd59a6ce876dab7b25690bf13e SHA-1: e284ed71da1678f2ef94b2d52176ecc25683a146 SHA-256: 9f047d077797fef3e1956da165de06a7c971e269383227ef0f2d0f77c4244ab7
240 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The RTF file contains an embedded OLE object that is related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The excessive hex data within the object data sections suggests that it is used to hide a payload. The file's structure and the specific heuristic firings strongly indicate exploitation of this vulnerability for client execution.

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 ~1764KB 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
  • 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_off00001037.bin
1f122bac5d0e9e0b61d4adef4fc15adc696464c751ac6c8edaa59371e46d3f56		 rtf-objdata-decoded RTF \objdata at offset 0x1037 882051 bytes

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