Malicious RTF — malware analysis report

Static analysis result for SHA-256 a1623479fcbdaace…

MALICIOUS

RTF

1.75 MB
MD5: 0d679bffcc7ad1acfd339fcdd7c4b8ef SHA-1: 77a81a1cacfa2b15fb1e5a3abc738ee14f093d5a SHA-256: a1623479fcbdaace5dcca0dfe2b643cc159a210725b8f7623eb37ec6482b4b90
260 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The RTF file contains OLE object data and specifically triggers heuristics related to CVE-2017-11882, indicating exploitation of the Equation Editor vulnerability. This vulnerability is known to be used to execute arbitrary code, likely to download and run a second-stage payload. The presence of OLE object data and excessive hex data further supports the payload delivery mechanism.

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 ~1828KB 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_off0000142a.bin
0f799fd06d7c6a3f2ee10c4a088696900e055f22fbb9d510648b723673405842		 rtf-objdata-decoded RTF \objdata at offset 0x142A 914251 bytes

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