CVE-2018-1062 in oVirt
Summary
by MITRE
A vulnerability was discovered in oVirt 4.1.x before 4.1.9, where the combination of Enable Discard and Wipe After Delete flags for VM disks managed by oVirt, could cause a disk to be incompletely zeroed when removed from a VM. If the same storage blocks happen to be later allocated to a new disk attached to another VM, potentially sensitive data could be revealed to privileged users of that VM.
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Analysis
by VulDB Data Team • 01/10/2020
The vulnerability identified as CVE-2018-1062 resides within the oVirt virtualization platform version 4.1.x prior to 4.1.9, representing a critical data exposure flaw that compromises the security of virtual machine disk management operations. This issue specifically manifests when administrators configure VM disks with both the Enable Discard and Wipe After Delete flags simultaneously, creating a dangerous condition in the storage allocation process that undermines data sanitization protocols. The vulnerability operates at the intersection of storage management and virtualization security, where improper handling of disk cleanup operations creates persistent data leakage risks across virtual environments.
The technical flaw stems from the improper implementation of disk zeroing procedures when disks are removed from virtual machines, particularly when both discard and wipe flags are enabled. When these flags are combined, the system fails to properly overwrite storage blocks with zeros before releasing them back to the storage pool, resulting in residual data remnants that persist on the physical storage medium. This occurs because the discard operation effectively marks blocks as unused while the wipe operation should ensure complete data erasure, but the interaction between these two mechanisms creates a race condition or logic flaw where the wiping process is either skipped or incomplete. The underlying issue aligns with CWE-242, which addresses the use of potentially dangerous functions, and specifically relates to improper handling of data sanitization processes in storage management systems.
The operational impact of this vulnerability extends beyond simple data exposure to create significant security implications for multi-tenant virtualization environments where multiple users or organizations share the same physical infrastructure. When storage blocks containing sensitive data from one VM are reallocated to another VM, privileged users of the new VM gain access to potentially confidential information from previous users, including system configurations, application data, user credentials, or business-sensitive information. This represents a serious violation of data isolation principles that virtualization platforms are designed to maintain, effectively creating a data leakage channel that could enable cross-tenant information disclosure attacks. The vulnerability particularly affects environments where VM disk management policies are automated or where administrators rely on default configurations without proper security awareness.
Mitigation strategies for CVE-2018-1062 require immediate patching of affected oVirt installations to version 4.1.9 or later, which contains the necessary fixes to properly handle the interaction between discard and wipe operations. Organizations should also implement strict disk management policies that avoid enabling both flags simultaneously, instead choosing either discard or wipe based on their specific security requirements and compliance mandates. The ATT&CK framework categorizes this vulnerability under T1486, which addresses data encryption for data destruction, and T1070, covering indicator removal on host, as the improper data sanitization creates persistent indicators of previous data usage. Additionally, organizations should conduct regular security audits of their virtualization environments, implement proper storage sanitization procedures, and establish monitoring protocols to detect potential data leakage events. Network segmentation and access controls should be reinforced to limit the potential impact of any successful exploitation attempts, while regular vulnerability assessments should include specific checks for similar issues in other virtualization management components.