Malicious RTF — malware analysis report

Static analysis result for SHA-256 242f18c830f27c12…

MALICIOUS

RTF

2.42 MB First seen: 2018-02-19
MD5: b47c88e1d148a163aebcaaf37bc94294 SHA-1: e038ced110cfb1c5ca242b88093a3e220fbf5a5c SHA-256: 242f18c830f27c12e0f01b638ef01cfe90ecbcebbf0d3cd371d5e2a2d6783228
342 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains OLE object data that forces activation of a remote loader, specifically leveraging CVE-2017-0199 or CVE-2017-8759. This loader is configured to download a payload from the URL http://localhost/t.php?stats=send&thread=0. The presence of VirtualAlloc and VirtualProtect API calls suggests the downloaded payload is likely to be executed in memory.

Heuristics 10

  • 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
  • Reference to VirtualAlloc API medium SC_STR_VIRTUALALLOC
    Reference to VirtualAlloc API
  • Reference to VirtualProtect API medium SC_STR_VIRTUALPROTECT
    Reference to VirtualProtect API
  • 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://localhost/t.php?stats=send&thread=0 In RTF body
    • http://ocsp.thawte.com0In RTF body
    • http://crl.thawte.com/ThawtePremiumServerCA.crl0In RTF body
    • http://crl.thawte.com/ThawteCodeSigningCA.crl0In 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: 226d83eb0f36f613936b891155fbcc1457c974a2156ee47cb98954f6e758b969
objdata_01_off0000dc96.bin rtf-objdata-decoded RTF \objdata at offset 0xDC96 2723 bytes
SHA-256: 6198c3d556447659345dcc52218a97045cd7489a6656373d62782c98761b3a8d

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