CVE-2011-1576 in Enterprise Virtualization Hypervisor
Summary
by MITRE
The Generic Receive Offload (GRO) implementation in the Linux kernel 2.6.18 on Red Hat Enterprise Linux 5 and 2.6.32 on Red Hat Enterprise Linux 6, as used in Red Hat Enterprise Virtualization (RHEV) Hypervisor and other products, allows remote attackers to cause a denial of service via crafted VLAN packets that are processed by the napi_reuse_skb function, leading to (1) a memory leak or (2) memory corruption, a different vulnerability than CVE-2011-1478.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/04/2024
The vulnerability described in CVE-2011-1576 represents a critical flaw in the Linux kernel's Generic Receive Offload implementation that affects Red Hat Enterprise Linux versions 5 and 6. This issue specifically targets the napi_reuse_skb function within the network stack processing pipeline, creating a remote attack vector that can be exploited through carefully crafted VLAN packets. The vulnerability operates at the kernel level, leveraging the fundamental network processing mechanisms that handle incoming packets and distribute them to network drivers for further processing.
The technical flaw manifests when the kernel's Generic Receive Offload mechanism processes malformed VLAN packets that trigger the napi_reuse_skb function. This function is responsible for reusing network buffer skbs (socket buffers) in the network processing pipeline, but due to improper handling of certain packet structures, it can either leak memory through improper buffer management or cause memory corruption through buffer overflows. The vulnerability is particularly dangerous because it operates at the kernel level where memory corruption can lead to system instability, crashes, or potentially privilege escalation. The flaw exists in kernel versions 2.6.18 and 2.6.32 respectively, indicating a long-standing issue that affected multiple kernel releases and corresponding enterprise virtualization environments.
From an operational impact perspective, this vulnerability enables remote attackers to perform denial of service attacks against systems running affected kernel versions, potentially causing complete system crashes or unresponsiveness. The attack requires only network access to send specially crafted VLAN packets, making it particularly dangerous in networked environments where systems may be exposed to untrusted network traffic. The memory leak aspect can gradually consume system resources over time, while the memory corruption component can lead to immediate system instability. This vulnerability is especially concerning for virtualization environments like Red Hat Enterprise Virtualization Hypervisor where multiple virtual machines share underlying physical resources, as a successful attack could potentially affect the entire host system.
The security implications of CVE-2011-1576 align with CWE-121, which addresses buffer overflow conditions in kernel space, and can be categorized under ATT&CK technique T1499.004 for network denial of service attacks. The vulnerability demonstrates how low-level kernel network processing functions can become attack surfaces when proper input validation and buffer management are not implemented. Organizations running affected systems should prioritize patching to address this vulnerability, as the attack vector is easily exploitable and the impact can be severe. The flaw also highlights the importance of proper kernel security testing and validation of network processing code, particularly in virtualized environments where multiple tenants share system resources. This vulnerability serves as a reminder of the critical importance of maintaining up-to-date kernel versions and implementing proper network segmentation to limit exposure to such attacks.