Malicious RTF — malware analysis report

Static analysis result for SHA-256 940b11262368859a…

MALICIOUS

RTF

1.82 MB
MD5: 821bdba880f060c0f71b6135c442f24f SHA-1: f602fca7dc874ef19ba71ee835ea44633b7b51e7 SHA-256: 940b11262368859aeb2b78ecd6b3e8373eae0421baac71d1ddc261e63cc894f4
220 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data, specifically related to Microsoft Equation Editor. Heuristics indicate a critical vulnerability, CVE-2017-11882, which is known to be exploited for client execution. The presence of large hex-encoded data blocks within the OLE object suggests it is used to hide a malicious payload. The file is likely delivered as a spearphishing attachment to exploit this vulnerability.

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 ~1909KB 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_off0000009f.bin
b93bdab546a5ee7d922aeb11b3338e80e38c72d5fb4eeec916992f5d06e3250b		 rtf-objdata-decoded RTF \objdata at offset 0x9F 955067 bytes

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