CVE-2020-9481 in ATS
Summary
by MITRE
Apache ATS 6.0.0 to 6.2.3, 7.0.0 to 7.1.9, and 8.0.0 to 8.0.6 is vulnerable to a HTTP/2 slow read attack.
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Analysis
by VulDB Data Team • 10/13/2020
The vulnerability identified as CVE-2020-9481 affects Apache Traffic Server versions ranging from 6.0.0 through 6.2.3, 7.0.0 through 7.1.9, and 8.0.0 through 8.0.6, specifically targeting the HTTP/2 protocol implementation within these software releases. This vulnerability represents a significant security concern as it exposes the traffic server to a sophisticated attack vector that can severely impact system performance and availability. The flaw manifests in how the server handles HTTP/2 connections, creating opportunities for malicious actors to exploit the protocol implementation through carefully crafted requests that consume excessive resources.
The technical nature of this vulnerability stems from insufficient input validation and resource management within the HTTP/2 handling code path of Apache Traffic Server. Attackers can leverage this weakness by establishing HTTP/2 connections and then deliberately reading data at a rate that is significantly slower than the server can process, effectively creating a resource exhaustion scenario. This slow read attack technique specifically targets the server's ability to manage concurrent connections and data flow, allowing attackers to consume memory and processing power without triggering immediate detection mechanisms. The vulnerability operates at the application layer and can be particularly insidious because it does not generate obvious network traffic patterns that would alert traditional security monitoring systems to the ongoing attack.
The operational impact of CVE-2020-9481 extends beyond simple performance degradation to potentially causing complete service disruption for affected systems. When exploited, this vulnerability can lead to denial of service conditions where legitimate users experience degraded service or complete inability to access resources through the affected traffic server. The attack can be executed with relatively minimal resources, making it accessible to threat actors with basic technical capabilities while still causing substantial damage to network infrastructure. Organizations relying on Apache Traffic Server for content delivery, load balancing, or proxy services face significant risk of operational disruption, especially those handling high volumes of HTTP/2 traffic. The vulnerability also creates potential for cascading failures in complex network architectures where multiple servers depend on the affected traffic server for proper operation.
Mitigation strategies for CVE-2020-9481 primarily involve upgrading to patched versions of Apache Traffic Server, specifically versions that have addressed the HTTP/2 slow read attack vulnerability. Organizations should also implement network-level protections such as rate limiting and connection throttling to reduce the impact of potential attacks. Monitoring systems should be enhanced to detect unusual patterns in HTTP/2 connection handling and data read rates, which can serve as early warning indicators of exploitation attempts. Additionally, implementing proper resource limits and connection timeouts can help prevent attackers from consuming excessive system resources. From a compliance standpoint, this vulnerability aligns with CWE-400, which covers unspecified resource management issues, and can be mapped to ATT&CK technique T1499.004 for network disruption attacks. Organizations should also consider implementing intrusion detection systems that can identify and alert on HTTP/2 protocol anomalies that may indicate exploitation attempts, particularly focusing on connection establishment patterns and data transfer rates that deviate from normal operational baselines.