Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 baea29755ad7d0d8…

MALICIOUS

Office (OLE) / .XLSX

162.2 KB First seen: 2022-06-28
MD5: 2f61395a0fe614c7eedf81c320828162 SHA-1: 5df8981874133d46ce0191a57708700c6388e3da SHA-256: baea29755ad7d0d89ae6ec2229bb06fafaf5a68869b3f07adad15e7020a79fd1
262 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1204 Malicious Link T1204.001 Malicious Link: Malicious Link T1059 Command and Scripting Interpreter T1071 Application Layer Protocol T1071.001 Application Layer Protocol: Web Protocols

The file is an encrypted Office document that leverages the CVE-2017-0199 vulnerability. It contains an embedded OLE object pointing to a remote URL, which is indicative of a downloader. ClamAV detection confirms this as a Formbook variant, likely designed to download and execute a second-stage payload.

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_16.doc

Open this report in the interactive analyzer, or submit your own file for analysis.