Описание
Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a "Permission denied" error when requesting a screenshot. That's because the Linux kernel has a security feature designed to block such attacks, protected_symlinks. On the rare systems with this purposefully disabled, it's then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue.
A flaw was found in Incus, a system container and virtual machine manager. A local attacker could exploit a vulnerability in the API responsible for retrieving VM screenshots. By creating symbolic links (symlinks) in predictable temporary file paths, an attacker could trick Incus into truncating and altering arbitrary files on the filesystem. This could lead to a denial of service or, in specific configurations where the protected_symlinks kernel security feature is disabled, a local privilege escalation.
Отчет
This Important flaw in Incus allows a local attacker to achieve denial of service or, under specific conditions, local privilege escalation. The vulnerability arises from predictable temporary file paths used during VM screenshot retrieval, enabling symlink attacks. On Red Hat Enterprise Linux, the protected_symlinks kernel security feature is enabled by default, which prevents the privilege escalation vector of this flaw.
Дополнительная информация
Статус:
EPSS
8.8 High
CVSS3
Связанные уязвимости
Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a "Permission denied" error when requesting a screenshot. That's because the Linux kernel has a security feature designed to block such attacks, `protected_symlinks`. On the rare systems with this purposefully disabled, it's then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue.
Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a "Permission denied" error when requesting a screenshot. That's because the Linux kernel has a security feature designed to block such attacks, `protected_symlinks`. On the rare systems with this purposefully disabled, it's then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue.
Incus is a system container and virtual machine manager. Incus provide ...
Incus vulnerable to local privilege escalation through VM screenshot path
Уязвимость системы управления контейнерами и менеджера виртуальных машин Incus, связанная с отслеживанием символьных ссылок, позволяющая нарушителю повысить свои привилегии
EPSS
8.8 High
CVSS3