Horizon Alert
Summary of the vulnerability and why it matters
This advisory describes a critical security vulnerability in ownCloud server's WebDAV component that could allow unauthorized access to user accounts. The issue involves insufficient protection against repeated login attempts, potentially enabling attackers to guess passwords for WebDAV accounts without needing any prior authentication. This could expose sensitive data and compromise account integrity.
- Bypasses authentication for account access.
- Exposes user accounts to guessing.
- Confirm relevance and exposure.
Attack Path
How an attacker could exploit the issue
An attacker can bypass authentication on ownCloud's WebDAV endpoint by repeatedly sending HTTP Basic Authentication requests. This allows them to guess passwords without any limitations, potentially leading to unauthorized access to sensitive files and system compromise.
- Unauthenticated remote access to WebDAV.
- Unlimited password guessing attempts.
- Bypass authentication, leading to data access.
Live Threat
Current exploitation, exposure, and threat context
An unauthenticated remote attacker could bypass authentication and guess passwords for WebDAV accounts on ownCloud servers. This could allow them to gain unauthorized access to files and potentially alter service behavior when the WebDAV endpoint is accessible over the network.
- Unauthorized access to WebDAV accounts.
- Repeated HTTP requests to guess passwords.
- Loss of data confidentiality and integrity.
Operational Fix
Recommended remediation, mitigation, and detection steps
Real-World Ownership
Addressing this critical vulnerability requires coordination between application owners responsible for ownCloud and infrastructure or platform teams managing the underlying servers. The immediate first step is to identify all instances of the affected ownCloud deployment, determine their internet reachability and business criticality, and then locate the accountable system owner to establish a remediation plan.
- Application and infrastructure teams own remediation.
- Verify internet-facing WebDAV endpoints first.
- Plan immediate risk reduction and patching.
