Formbook Office (OLE) / .XLSX malware analysis — malicious · 7136f281b99f09b2

MALICIOUS

Office (OLE) / .XLSX

83.5 KB First seen: 2022-08-20

MD5: 84352567ae34896eea815d2791353106 SHA-1: 258b21be124f1b68bc4942d8fed2d65466012cf6 SHA-256: 7136f281b99f09b298a5ce0ba8b8cf88c70a27f9c14f43ca18e729d93177819d

202 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK

T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.001 Command and Scripting Interpreter: PowerShell T1190 Exploit Public-Facing Application

The sample is a password-encrypted Office document that exploits CVE-2017-0199 via an embedded OLE object. This vulnerability allows it to act as a remote loader, downloading a second-stage payload from the URL http://192.227.228.33/https/www.doc. ClamAV detection confirms this is a Formbook downloader.

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://192.227.228.33/https/www.doc

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