FormBook — RTF malware analysis

Static analysis result for SHA-256 dcab4a46f6e62cfa…

MALICIOUS

RTF

417.2 KB First seen: 2018-10-07
MD5: f6ade2b3bbeb466fe364a47b93ba4ac7 SHA-1: 532a85dda332d38efb99936beb8032f1212fc4f5 SHA-256: dcab4a46f6e62cfaad2b8e7b9d1d8964caaadeca15790c6e19b9a18bc3996e18
220 Risk Score

Malware Insights

FormBook · confidence 95%

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

The RTF file contains OLE object data and triggers critical heuristics for CVE-2017-8759 (SOAP Moniker RCE). ClamAV identifies the file as Rtf.Dropper.FormBook, indicating it's a dropper for the FormBook information-stealer. The embedded OLE object is likely responsible for executing the exploit and downloading the secondary payload.

Heuristics 5

  • SOAP Moniker — CVE-2017-8759 (SOAP WSDL RCE) critical CVE related CVE_2017_8759
    RTF \objdata decodes to OLE data containing the SOAP Moniker — CVE-2017-8759 (SOAP WSDL RCE) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • ClamAV: Rtf.Dropper.FormBook-6749871-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.FormBook-6749871-0
  • 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 73447 bytes
SHA-256: cb8541d388bb5260a993c1d2bf3a31a20112810f34d1a56eb3529a4227966687