Malicious RTF — malware analysis report

Static analysis result for SHA-256 f38294c2ea0fc78c…

MALICIOUS

RTF

529.7 KB First seen: 2017-11-29
MD5: 1686a4e622150b7a1df8362a7083d450 SHA-1: d7d121bfb48ee18730498872b1f40b9e749683ff SHA-256: f38294c2ea0fc78c57d0637b8ba219bd91d12435100702fb7d9bd139539b6a43
222 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains OLE object data with an \objupdate directive, indicating an attempt to automatically activate embedded objects. This is a known technique for exploiting vulnerabilities like CVE-2017-0199 and CVE-2017-8759. The embedded OLE object attempts to load a remote payload from the URL http://kinesk.com/t/t.php?stats=send&thread=2, which is a strong indicator of a downloader malware.

Heuristics 6

  • 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 or the OLE object's own moniker. This is the 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
  • \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://kinesk.com/t/t.php?stats=send&thread=2 In RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000c568.bin rtf-objdata-decoded RTF \objdata at offset 0xC568 2598 bytes
SHA-256: 831d653a8bf6b35f70c34b8f0aa9b4deff313b9e99f06c2a160f156cfbe686ed
objdata_01_off0000dc96.bin rtf-objdata-decoded RTF \objdata at offset 0xDC96 2674 bytes
SHA-256: b2d1dcd53ab72d489708eb5449a9c003c690279daf375b527c7e12791399d9fe

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