Malicious RTF — malware analysis report

Static analysis result for SHA-256 fd42351e315937ac…

MALICIOUS

RTF

8.4 KB Authoring application: Riched20 6.3.9600 First seen: 2018-11-13
MD5: c3927c2154aadba53edbeb88b7ab46ac SHA-1: 99874d618588da353de6c523c81f64cf739333d7 SHA-256: fd42351e315937ac800c3899d32b7344fa6e5f561e91a70f4357b5bbab871aad
322 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This vulnerability allows for arbitrary code execution when the object is activated, likely through a ".objupdate" directive. The exploit is confirmed by multiple critical heuristic firings and ClamAV detection.

Heuristics 8

  • 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: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://s3.amazonaws.com/icee/ParT.hta In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000fe.bin rtf-objdata-decoded RTF \objdata at offset 0xFE 3546 bytes
SHA-256: a7284eb3ccf856878e49c774d41c5af6535094c1ce10a18b682003cff4f6d8be

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