Malicious RTF — malware analysis report

Static analysis result for SHA-256 b92d773a2e94f4f2…

MALICIOUS

RTF

968.2 KB Created: 2017-12-19 14:32:00 First seen: 2018-01-08
MD5: 1be760ebea124f8b35a75db9efc4b82e SHA-1: 9ebb31a9f9512e25950b84b72aa06424266361ce SHA-256: b92d773a2e94f4f26466f9e6f000b34666336506f54d02141cb313aec298442a
382 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains embedded OLE object data and uses \objupdate to force OLE activation, indicating an attempt to exploit vulnerabilities. Specifically, the CVE-2017-8759 heuristic firing points to a known exploit targeting MSXML SAX OLE activation. The file also references a remote URL via the INCLUDETEXT/INCLUDEPICTURE mechanism, which is likely used to download a secondary payload. ClamAV detection as Rtf.Downloader.CVE_2017-6336326-3 further confirms its malicious downloader nature.

Heuristics 10

  • 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: Rtf.Downloader.CVE_2017-6336326-3 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Downloader.CVE_2017-6336326-3
  • Reference to CreateProcess API high SC_STR_CREATEPROCESS
    Reference to CreateProcess API
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • \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.
  • INCLUDETEXT/INCLUDEPICTURE remote URL high RTF_INCLUDE_REMOTE
    RTF document uses INCLUDETEXT or INCLUDEPICTURE with an http:// URL — Word can fetch the remote content on open depending on Office version and external-content settings, enabling remote template injection, NTLM capture via redirects, or payload delivery
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • 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://nsis.sf.net/NSIS_Error In RTF body
    • http://kristinaslip1.000webhostapp.com/t.php?stats=send&thread=0In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00042c07.bin rtf-objdata-decoded RTF \objdata at offset 0x42C07 2598 bytes
SHA-256: 2cb1ad33bbdccbf6f94b7145ae8d71dd195fba677b709ebb7802f3188663d53b
objdata_01_off00044335.bin rtf-objdata-decoded RTF \objdata at offset 0x44335 2723 bytes
SHA-256: 7322d9b1f1bae657e6a0ad1b6fb31496497e614b42e4ce47d5a19ba8537ec4e4

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