CVE-2018-1118 in Linux
Summary
by MITRE
Linux kernel vhost since version 4.8 does not properly initialize memory in messages passed between virtual guests and the host operating system in the vhost/vhost.c:vhost_new_msg() function. This can allow local privileged users to read some kernel memory contents when reading from the /dev/vhost-net device file.
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Analysis
by VulDB Data Team • 03/11/2023
The vulnerability identified as CVE-2018-1118 affects the Linux kernel's vhost implementation, specifically targeting versions 4.8 and later. This flaw resides in the vhost/vhost.c file within the vhost_new_msg() function where memory initialization processes fail to properly sanitize data structures before passing messages between virtual guests and the host operating system. The issue represents a classic information disclosure vulnerability that arises from improper memory handling within virtualization components.
The technical root cause of this vulnerability stems from inadequate memory initialization practices in the vhost subsystem which manages virtual host interfaces for virtio devices. When local privileged users interact with the /dev/vhost-net device file, the system fails to properly clear or initialize memory regions that contain sensitive kernel data. This memory leakage occurs because the vhost_new_msg() function does not ensure that all memory fields are properly initialized before being populated with data from virtual machine contexts. The flaw allows attackers to potentially extract kernel memory contents through read operations on the device file, creating a pathway for information disclosure attacks.
From an operational impact perspective, this vulnerability poses significant risks to virtualized environments where local privileged users already have elevated access rights. While the vulnerability requires local privileged access rather than remote exploitation, it can enable attackers to gain insights into kernel memory structures, potentially revealing sensitive information such as stack contents, kernel pointers, or other confidential data. The implications extend beyond simple information disclosure as this leaked memory could contain cryptographic keys, passwords, or other sensitive data that might aid in further exploitation attempts. This vulnerability directly impacts the confidentiality and integrity of virtualized systems, particularly affecting cloud computing environments where multiple tenants share the same physical infrastructure.
The vulnerability aligns with CWE-1289 which categorizes improper initialization of memory and relates to the broader class of information disclosure flaws. From an attack framework perspective, this issue can be mapped to ATT&CK technique T1005 (Data from Local System) and potentially T1059 (Command and Scripting Interpreter) as attackers might leverage the leaked information to refine their attack vectors. The exploitation requires local privileged access, which means attackers would typically need to first compromise a user account with sufficient privileges to access the vhost-net device. Mitigation strategies should focus on applying kernel patches that properly initialize memory structures in the vhost_new_msg() function and implementing proper access controls to limit privileged access to virtualization interfaces. Organizations should also consider monitoring for unusual read operations on the /dev/vhost-net device file and implementing kernel hardening measures to reduce the attack surface of virtualization components.