Formbook — Office (OLE) / .XLSX malware analysis

Static analysis result for SHA-256 61ba4add05b63a3b…

MALICIOUS

Office (OLE) / .XLSX

150.7 KB First seen: 2022-07-08
MD5: daac974c2b9a04eaef24eb180a34b67c SHA-1: 4aee01effbfb22f2a900372d1805d0c75d6dd03b SHA-256: 61ba4add05b63a3b9d93e763b80600d091f610303c753f0dbb38cc3149e76680
262 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is a password-encrypted Office document that leverages CVE-2017-0199 to load a remote resource. The embedded URL, http://www.javatpoint.com@3236145346/swift_copy/inv01/receipt.doc, is likely used to download a second-stage payload. ClamAV detection confirms this is a downloader associated with the Formbook family.

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://www.javatpoint.com@3236145346/swift_copy/inv01/receipt.doc

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