Formbook Office (OLE) / .XLSX malware analysis — malicious · 15f084eb35d319bd

MALICIOUS

Office (OLE) / .XLSX

96.5 KB First seen: 2022-08-24

MD5: 6c957a80e23e31d74a490b2cb55e7fb5 SHA-1: 3618a05a4267f2becf6b1ae02267bbaf34f0b143 SHA-256: 15f084eb35d319bda0e7675e673ccafba32b64adeac35708afb0385221c22da7

202 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK

T1204 Malicious Link T1204.001 Malicious Link: User Execution T1059 Command and Scripting Interpreter T1059.001 Command and Scripting Interpreter: PowerShell T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1566.002 Phishing: Spearphishing Link

The sample is an encrypted Office document that exploits CVE-2017-0199 via an OLE2Link object. This exploit is designed to download and execute a remote payload from the URL http://jmcglone.com@192.3.108.11/office/https_k/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://jmcglone.com@192.3.108.11/office/https_k/www.doc

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