Malicious RTF — malware analysis report

Static analysis result for SHA-256 77a2d8e84206a20f…

MALICIOUS

RTF

261.1 KB Created: 2018-07-03 09:28:00 First seen: 2019-11-20
MD5: 63aca7dc6bd828794a36fd065b2e95cd SHA-1: 0428d5ba3f59ed537b5ff4de67403276c12fc310 SHA-256: 77a2d8e84206a20f8a799d2b2789e7082f389fa0fcbda578e53aae895a20e068
262 Risk Score

Malware Insights

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

The RTF file contains critical heuristic firings for CVE-2017-11882 and CVE-2017-8759, indicating exploitation of these vulnerabilities. The presence of OLE object data and an embedded URL suggests the file is designed to download and execute a secondary payload, likely a MSI installer, from the provided URL. The ClamAV detection further confirms its malicious nature.

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://schemas.microsoft.com/office/word/2003/wordml In RTF body
    • https://compute-1.azurewebsites.net/cc.msiIn 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: ff0f367e4c76414277282905265e38fcadfe2b3a26ab86479e36633c10dc0f18

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