CVE-2010-4247 in xen
Summary
by MITRE
The do_block_io_op function in (1) drivers/xen/blkback/blkback.c and (2) drivers/xen/blktap/blktap.c in Xen before 3.4.0 for the Linux kernel 2.6.18, and possibly other versions, allows guest OS users to cause a denial of service (infinite loop and CPU consumption) via a large production request index to the blkback or blktap back-end drivers. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 10/11/2021
The vulnerability identified as CVE-2010-4247 represents a critical denial of service flaw affecting the Xen hypervisor's block I/O subsystem. This issue resides within the do_block_io_op function implementation in two key driver files: drivers/xen/blkback/blkback.c and drivers/xen/blktap/blktap.c. The vulnerability specifically impacts Xen versions prior to 3.4.0 when operating with Linux kernel 2.6.18 and potentially other versions, creating a significant security risk for virtualized environments. The flaw manifests when guest operating systems submit maliciously large production request indexes to the blkback or blktap back-end drivers, leading to system instability and resource exhaustion.
The technical root cause of this vulnerability stems from inadequate input validation within the block I/O operation handling mechanism. When a guest OS user submits an oversized production request index, the do_block_io_op function fails to properly validate the input parameters before processing them. This validation gap allows the malicious input to trigger an infinite loop condition within the driver's processing logic, causing continuous CPU consumption without proper termination conditions. The flaw operates at the hypervisor level, affecting the core block storage functionality that connects guest operating systems to virtualized storage devices. The vulnerability is particularly dangerous because it can be exploited by any user within a guest OS, requiring no elevated privileges to cause system-wide disruption.
The operational impact of CVE-2010-4247 extends beyond simple service disruption to create substantial system instability in virtualized environments. When exploited, the infinite loop consumes CPU resources continuously, potentially leading to complete system unresponsiveness or degradation of service for all virtual machines running on the affected hypervisor. This type of denial of service attack can be particularly devastating in cloud computing environments where multiple tenants share the same physical infrastructure. The vulnerability affects the fundamental block I/O operations that virtual machines rely upon for storage access, making it a critical threat to virtualization security. Organizations running Xen hypervisors without proper patching are at risk of experiencing complete service outages that can affect multiple virtual machines simultaneously.
Mitigation strategies for this vulnerability require immediate patching of affected Xen versions to 3.4.0 or later, which includes the necessary input validation fixes. System administrators should also implement monitoring solutions to detect unusual CPU consumption patterns that might indicate exploitation attempts. Additional defensive measures include limiting guest OS privileges, implementing resource quotas for virtual machines, and conducting regular vulnerability assessments of virtualization infrastructure. The vulnerability aligns with CWE-129, which addresses insufficient input validation, and maps to ATT&CK technique T1499.004 for resource hijacking. Organizations should also consider implementing network segmentation and access controls to limit potential attack vectors, while maintaining regular security updates to address similar vulnerabilities in virtualization components. The incident underscores the importance of proper input validation in hypervisor components and the critical need for timely patch management in virtualized environments.