Malicious RTF — malware analysis report

Static analysis result for SHA-256 bb61b83923733ef3…

MALICIOUS

RTF

189.6 KB First seen: 2017-12-08
MD5: 6389048fc255e78660c69877afff89c3 SHA-1: e4843fde54b1899d492e41af75a058134cdc9e56 SHA-256: bb61b83923733ef3bcf0e1a0938b7b288fb3181648b7f19de46022b8f332efb7
160 Risk Score

Malware Insights

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

The RTF file contains OLE object data that is automatically linked and force-activated via \objupdate. This indicates exploitation of CVE-2017-0199 or CVE-2017-8759, which allows for the automatic loading and execution of a remote payload embedded within the OLE moniker stream. The specific vulnerabilities exploited are identified as CVE-2017-0199 and CVE-2017-8759.

Heuristics 4

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003f.bin rtf-objdata-decoded RTF \objdata at offset 0x3F 2608 bytes
SHA-256: d99738edba3e8c86be0fbbde50ce916b0fb690840b495b74a6ebebe7f2d996e7

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