Malicious RTF — malware analysis report

Static analysis result for SHA-256 4fde75b56453988d…

MALICIOUS

RTF

2.40 MB
MD5: 91d4d4d32626a2616793995d75186e83 SHA-1: d51aa0c655253c5e269c2f087b5584d79788b844 SHA-256: 4fde75b56453988d41bf6d54d747b0c6c942fa68bfae01f86a17ee43a923a8e5
220 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and critical heuristics indicate the exploitation of CVE-2017-11882 via Microsoft Equation Editor. This vulnerability is known to be used for arbitrary code execution, suggesting the file is designed to deliver a second-stage payload. The large amount of hex-encoded data within the OLE object further supports the presence of a hidden payload.

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 ~2511KB 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_off000000be.bin
0193caaf519d24ee1abee94da59a7f914ef0725e5afb0d97009d2f5aa7bc0988		 rtf-objdata-decoded RTF \objdata at offset 0xBE 1004805 bytes

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