Horizon Alert
Summary of the vulnerability and why it matters
A flaw in the Go crypto library could allow a malicious SSH peer to disrupt connections. This occurs when unsolicited responses fill an internal buffer, preventing the connection from functioning correctly. The impact of this vulnerability can lead to resource leaks within affected systems.
- Vulnerable: Go crypto library
- Flaw: Unsolicited responses fill buffer
- Impact: Connection disruption and resource leaks
Attack Path
How an attacker could exploit the issue
This vulnerability arises when a malicious SSH peer sends unsolicited global request responses. These responses can fill an internal buffer, causing the connection's read loop to become blocked. This blocked state prevents the goroutine from being released, even when `Close()` is called, leading to a resource leak for each affected connection. The vulnerability has been addressed by discarding unsolicited global responses.
- Exposure condition: Network access to SSH.
- Attacker starting point: Malicious SSH peer.
- Trigger and result: Unsolicited responses block connections, leak resources.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability could allow a malicious SSH peer to disrupt connections, leading to resource leaks. The impact primarily affects the availability of services that rely on the affected Go crypto library for SSH functionality. Organizations using this library should address this issue to maintain service stability.
- Likely attacker skill level: Low
- Required access or conditions: Network access
- Business risk or urgency: High
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
A vulnerability exists in the golang.org/x/crypto library that could lead to resource leaks and connection blocking if a malicious SSH peer sends unsolicited global request responses. This issue impacts internal buffers and can prevent connections from closing properly, potentially affecting system stability and availability. The vendor has addressed this by discarding unsolicited global responses.
- Identify assets using the affected library.
- Reduce exposure if assets are internet-facing.
- Apply the vendor fix and validate.
- Monitor systems for related issues.
