Malicious RTF — malware analysis report

Static analysis result for SHA-256 26d28a35b174094b…

MALICIOUS

RTF

261.1 KB Created: 2018-07-03 09:28:00 First seen: 2019-09-30
MD5: 746af081c9e8121728c56c6c14a93123 SHA-1: c1ce05944dabb7fc8fe9c408b963cbf9c1206b87 SHA-256: 26d28a35b174094ba37d3cdf1be0b4157ac2620a81723714aa8b6a305e6e6639
262 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and triggers critical heuristics for CVE-2017-11882 (Equation Editor FONT record overflow) and CVE-2017-8759 (MSXML SAX OLE activation). These vulnerabilities are exploited to execute a malicious MSI installer downloaded from an unknown URL. The file is identified as malicious by ClamAV with a specific detection name related to CVE-2017-11882.

Heuristics 7

  • 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.
  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    RTF contains a hex-encoded OLE1 object for Msxml2.SAXXMLReader.6.0 followed by an embedded OLE compound document, and the document requests OLE activation. This matches the RTF staging shape used for CVE-2017-8759 SOAP/WSDL parser code injection.
  • ClamAV: Doc.Exploit.Cve_2017_11882-7570663-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Exploit.Cve_2017_11882-7570663-1
  • \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 http://nathanlaprie.fr/wp-includes/js/tinymce/plugins/wplink/app/anvhvy.msi In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000bf6b.bin rtf-objdata-decoded RTF \objdata at offset 0xBF6B 15672 bytes
SHA-256: c15b66838171ac03fdab8fd3090dc7254325b31c95e2ce2e9480b2a44601f8c3

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