Malicious RTF — malware analysis report

Static analysis result for SHA-256 cb2675ed3fb8e0cc…

MALICIOUS

RTF

42.1 KB First seen: 2019-11-20
MD5: 7abb2e0e9e4d5fc0b1d6be5fb830d4c1 SHA-1: 51f0112a1ba0ed7d96a78014acb60c791e847a52 SHA-256: cb2675ed3fb8e0cc9ed6a48ca9bdfdf706d18ce8bf34c3ba2248a8d32a87d650
240 Risk Score

Malware Insights

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

The sample is an RTF document that contains embedded OLE object data, specifically targeting the Equation Editor component. Critical heuristics indicate a successful exploitation of CVE-2017-11882 via a FONT record overflow, which is a common method for achieving arbitrary code execution. The ".objupdate" heuristic suggests the exploit is designed to trigger automatically upon opening the document, likely leading to the download and execution of a secondary malicious payload. No specific family could be identified, but the exploit vector is highly indicative of a malicious document used in targeted attacks.

Heuristics 5

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • ClamAV: Doc.Exploit.CVE_2017_11882-6934206-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.CVE_2017_11882-6934206-0
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001bfd.bin rtf-objdata-decoded RTF \objdata at offset 0x1BFD 11873 bytes
SHA-256: bd5786d4e95810b4c964c3535af218a75669aee7465e8fa1d275feba5d8c48e6

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