Malicious RTF — malware analysis report

Static analysis result for SHA-256 cf0d694e17f0616c…

MALICIOUS

RTF

613.2 KB First seen: 2018-03-04
MD5: 897211447467437211a358a4950b8f9e SHA-1: dc100b0cace2286d3e7e2c899208e6768506af88 SHA-256: cf0d694e17f0616cbfb4dd55d7cd6420e8273a5b339a886f9db37b445cd6eaa7
302 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains OLE object data that triggers remote code execution via OLE2Link. This is indicative of exploitation for client execution, likely through a vulnerability such as CVE-2017-0199 or CVE-2017-8759. The embedded URL http://91.225.216.83/t.php?stats=send&thread=0 is used to download a secondary payload, which is a common technique for malware distribution.

Heuristics 8

  • CVE-2017-0199 / CVE-2017-8759 (OLE2Link auto-activated remote loader) critical CVE related RTF_OLE2LINK_REMOTE_MONIKER_LOADER
    RTF embeds an OLE2Link object that is force-activated with \objupdate (no user interaction on open) and fetches a remote second stage through an INCLUDETEXT/INCLUDEPICTURE field. This is the field-delivered OLE2Link auto-update attack path shared by CVE-2017-0199 (server returns an HTA/scriptlet) and CVE-2017-8759 (server returns a SOAP WSDL the .NET parser compiles). Office processes the fetched response through the same code path; the specific CVE depends on the now-unreachable server content type.
  • ClamAV: Rtf.Downloader.CVE_2017-6336326-3 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Downloader.CVE_2017-6336326-3
  • 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://91.225.216.83/t.php?stats=send&thread=0 In RTF body
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn RTF body
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliographyIn RTF body
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000c4a4.bin rtf-objdata-decoded RTF \objdata at offset 0xC4A4 2598 bytes
SHA-256: 7741a1bf196ccc45846a542827dbfcaffed23b70146346e61dccd7b0ecdbad45
objdata_01_off0000dbd2.bin rtf-objdata-decoded RTF \objdata at offset 0xDBD2 2723 bytes
SHA-256: d5cfeb64b06c7295e50887aec1056472c2859291ff0b223008add67ef9f75b56

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