Formbook Office (OLE) / .XLSX malware analysis — malicious · c315fa07a21e6403

MALICIOUS

Office (OLE) / .XLSX

90.5 KB First seen: 2022-08-23

MD5: c93faad02944b1e3ca7add62cfe89da4 SHA-1: 4e3769fb6fd792f3272ca6fa28e299a3357cbe1c SHA-256: c315fa07a21e6403109b6bea4eda2c230e21e6bc3c9d5ac86105542ffee1b77b

202 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK

T1204 Malicious Link T1204.001 Malicious Link: Malicious Link T1059 Command and Scripting Interpreter T1059.001 Command and Scripting Interpreter: PowerShell

The sample is a password-encrypted OOXML file that exploits CVE-2017-0199 via an OLE2Link object. This technique is commonly used to download and execute a second-stage payload from a remote URL. ClamAV detection confirms this as a Formbook downloader. The embedded URL is the primary indicator of compromise.

Heuristics 6

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.
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://jmcglone.com@192.227.132.34/www/57.doc

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