Formbook Office (OLE) / .XLSX malware analysis — malicious · 162aec62f8441521

MALICIOUS

Office (OLE) / .XLSX

162.4 KB First seen: 2022-06-29

MD5: 02da7e098d59890a63ff7350650050f5 SHA-1: f044ebd016daf2552b825db4fc80a33214a8b71d SHA-256: 162aec62f84415216690c9a6d4b2c287737dfc4a832497d56a88059e8a5a5837

262 Risk Score

Malware Insights

Formbook · confidence 95%

MITRE ATT&CK

T1203 Exploitation for Client Execution

The file is an encrypted Office document that exploits CVE-2017-0199, acting as a loader for a remote document. The embedded URL points to a potential second-stage payload, and ClamAV detection identifies it as a Formbook downloader. The exploitation of a known vulnerability and the download mechanism strongly indicate a malicious intent.

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://riteshkhan.github.io@192.227.168.194/office_dc/bb_receipt.doc

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