Malicious RTF — malware analysis report

Static analysis result for SHA-256 44fea1d943501ce1…

MALICIOUS

RTF

5.44 MB First seen: 2019-04-18
MD5: 2e56c9f6c57e2d49d02f26675109473c SHA-1: 128b714488768bea5df8ee08ecd6e9e46e2d89ab SHA-256: 44fea1d943501ce1163fb7e3c152190bd419f4e6aa56ac5052eaf0f2e557bdef
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 updated, indicating an attempt to exploit vulnerabilities like CVE-2017-0199 or CVE-2017-8759. This mechanism is used to force the activation of an OLE2Link object, which then loads a second-stage payload from a remote source embedded within the OLE moniker stream. The document body is heavily obfuscated and does not provide clear textual lures.

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_off004b288e.bin rtf-objdata-decoded RTF \objdata at offset 0x4B288E 3117 bytes
SHA-256: fd7aada3b2c238d84270aae56921494f37934affe57a307352a756e7c1478ea6

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