Office (OLE) / .XLSX malware analysis — malicious · bf3549cc255f7352

MALICIOUS

Office (OLE) / .XLSX

71.3 KB First seen: 2022-06-27

MD5: 51cfe921d2e3ef501e90ed54b358b290 SHA-1: 0d05efcfe87ea8e43cf16293a2ea413ffa99273c SHA-256: bf3549cc255f73526ffb5e744c0e2c5d838a303f6f59d3ad4b9d1c01c0cbf185

202 Risk Score

Malware Insights

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 an encrypted Office document that exploits CVE-2017-0199 via an embedded OLE object. This vulnerability allows it to act as a remote loader, fetching and executing a secondary payload from the URL http://blooket.github.io@192.210.240.12/80/office.doc. The document's encrypted nature and the critical heuristic firings strongly indicate a malicious intent to deliver further malware.

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.
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.
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://blooket.github.io@192.210.240.12/80/office.doc

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