CVE-2011-4609 in C Library
Summary
by MITRE
The svc_run function in the RPC implementation in glibc before 2.15 allows remote attackers to cause a denial of service (CPU consumption) via a large number of RPC connections.
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Analysis
by VulDB Data Team • 01/02/2022
The vulnerability identified as CVE-2011-4609 represents a critical flaw in the GNU C Library's RPC implementation that affects systems running glibc versions prior to 2.15. This issue specifically targets the svc_run function which serves as the core service loop for handling Remote Procedure Call connections. The vulnerability stems from inadequate connection handling mechanisms that fail to properly manage resource allocation when processing multiple simultaneous RPC requests, creating a pathway for malicious actors to exploit the system's processing capabilities through excessive connection attempts.
The technical nature of this vulnerability aligns with CWE-400, which categorizes it as an Uncontrolled Resource Consumption issue. The flaw occurs because the svc_run function in glibc lacks proper rate limiting and connection management controls that would normally prevent a single process from consuming excessive CPU cycles through repeated connection attempts. Attackers can exploit this weakness by establishing a large number of RPC connections simultaneously, causing the system to spend disproportionate amounts of CPU time in connection handling rather than performing legitimate operations. This type of attack directly maps to the ATT&CK technique T1499.004, which involves resource exhaustion attacks targeting system services.
The operational impact of CVE-2011-4609 extends beyond simple denial of service conditions, as it can severely degrade system performance and potentially render services unavailable to legitimate users. When exploited, the vulnerability causes the target system to consume excessive CPU resources, leading to cascading performance issues that may affect other running applications and services. The vulnerability is particularly dangerous in networked environments where RPC services are commonly exposed to external traffic, as it allows attackers to perform resource exhaustion attacks without requiring authentication or specialized privileges. Systems running older versions of glibc become vulnerable to this attack vector because they lack the improved connection handling mechanisms that were implemented in version 2.15 and later releases.
Mitigation strategies for this vulnerability primarily focus on upgrading to glibc version 2.15 or later, which includes enhanced connection management and resource allocation controls. System administrators should also implement network-level protections such as connection rate limiting, firewall rules that restrict RPC service access, and monitoring systems that can detect unusual connection patterns. Additionally, organizations should consider implementing service-level protections like connection pooling and timeout mechanisms to limit the impact of potential attacks. The vulnerability demonstrates the importance of maintaining up-to-date system libraries and implementing proper resource management controls in network services, as it represents a classic example of how insufficient input validation and resource handling can create exploitable conditions in system-level software components.