Office (OLE) / .XLSX malware analysis — malicious · b34b9fa2da261d4c

MALICIOUS

Office (OLE) / .XLSX

58.0 KB First seen: 2022-07-26

MD5: 6da91b62025790d7e65dbe3b061697a6 SHA-1: 34570dd5dccb2ea21eb318bf4564c6e4619cf210 SHA-256: b34b9fa2da261d4c15efa66548dee6f597a3c2f9f57add9842044813dd9efd53

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 T1190 Exploit Public-Facing Application

The file is an encrypted Office document that leverages the CVE-2017-0199 vulnerability. This vulnerability allows it to act as a remote loader, fetching and likely executing a secondary malicious document from the embedded URL http://23.95.52.140/office/doc5/doc5.docx. The ClamAV detection further confirms its malicious nature as a 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: Xls.Downloader.94c25b356b5a6cac-9978798-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.94c25b356b5a6cac-9978798-0
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://23.95.52.140/office/doc5/doc5.docx

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