Horizon Alert
Summary of the vulnerability and why it matters
This advisory concerns a security flaw in the widely used `curl` data transfer tool. The issue involves how `curl` handles user credentials when following redirects during a specific type of authentication, potentially exposing sensitive information to unintended destinations. While the likelihood of exploitation via public internet is low, it highlights a potential risk in how credentials are managed in certain data transfer scenarios.
- Sensitive credentials may leak on redirects.
- This affects how users authenticate sensitive data.
- Confirm relevance and exposure of `curl` usage.
Attack Path
How an attacker could exploit the issue
An attacker could exploit this by tricking a user's curl client into making an initial authenticated request to a legitimate server, which then redirects to a malicious server. The curl client, when following this redirect during the initial transfer with Negotiate authentication, may inadvertently send the user's credentials to the attacker-controlled server. This could allow an attacker to impersonate the user or access sensitive information.
- Requires an ambient user and specific authentication.
- Vulnerable when following redirects with Negotiate.
- Risk of credential leakage and impersonation.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow sensitive credential details to be passed to an unintended website when curl is used for authenticated transfers that involve following redirects. This affects situations where an ambient user's credentials are used for an initial transfer and the system is then prompted to redirect to a different origin.
- Credential details could be exposed.
- Occurs when following redirects after authentication.
- Unintended information disclosure.
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability in curl could allow an attacker to trick a client into sending credentials to an unintended server during a redirected transfer. Ownership typically falls to the teams managing client-side tooling, application development, or any operational technology that utilizes curl for data transfers. The initial step involves identifying all systems and applications using curl in a manner susceptible to this redirect behavior, assessing the business criticality and exposure of these instances, and then coordinating remediation with the relevant application or system owners.
- Application or tooling owners should address this.
- Verify curl usage with redirects and authentication.
- Plan updates during scheduled maintenance windows.
