Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 9ca1a8a11d292f49…

MALICIOUS

Office (OLE) / .XLSX

162.3 KB First seen: 2022-06-28
MD5: dda413e09bda04f5bedfd6cc48915414 SHA-1: 63a154732baf20c8d82f8a00ffdb7dcd1e82bc3f SHA-256: 9ca1a8a11d292f491a196ea2a684e3999b6901488ffa1ce834cada2f564ac7c5
262 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204 Malicious File Execution T1204.002 Malicious File Execution: Malicious Attachment T1059 Command and Scripting Interpreter T1190 Exploit Public-Facing Application

The file is an encrypted Office document that leverages the CVE-2017-0199 vulnerability via an embedded OLE object. This vulnerability allows for the remote loading of a document from the URL http://blooket.github.io@192.227.168.194/office_dc/invc_21.doc, which is likely a second-stage payload. ClamAV detection confirms this as a Formbook downloader.

Heuristics 7

  • OLE2Link / URL Moniker → remote loader — CVE-2017-0199 critical CVE likely CVE_2017_0199
    Document contains an embedded OLE link object whose URL Moniker points to a remote URL. When the host file is opened, Office follows the link, downloads the URL, and processes the response based on its Content-Type (HTA -> mshta.exe, RTF → Word, etc.) — the documented CVE-2017-0199 primitive. The URL extension is not a reliable filter; servers can return different payloads to Office's user agent.
  • Encrypted Office package with CFB FAT corruption critical OLE_ENCRYPTED_AND_MALFORMED
    Encrypted-package shape co-occurs with FAT-chain corruption — the documented combined evasion form.
  • ClamAV: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Doc.Downloader.Formbook-bc97c1e0c33c3c93-9951465-0
  • Default-encrypted OOXML exploit carrier layout high OOXML_ENCRYPTED_EXPLOIT_CARRIER_SHAPE
    Default-password encrypted OOXML package contains embedded OLE object parts and additional activation/decoy parts. This layout is common in malicious Excel exploit delivery and requires inspecting the decrypted package.
  • Office document is password-encrypted medium OFFICE_ENCRYPTED_PACKAGE
    OLE container holds MS-OFFCRYPTO encrypted package (Standard Encryption (Office 2007, AES)).
  • Office OOXML encrypted with default VelvetSweatshop password medium OFFICE_DEFAULT_PASSWORD_ENCRYPTED_OOXML
    OLE EncryptedPackage decrypts with Excel's built-in VelvetSweatshop password. Office opens this transparently, and malware uses it to hide OOXML exploit parts from scanners that only inspect the outer OLE container.
  • 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://blooket.github.io@192.227.168.194/office_dc/invc_21.doc