CVE-2023-6200
Description
A race condition was found in the Linux Kernel. Under certain conditions, an unauthenticated attacker from an adjacent network could send an ICMPv6 router advertisement packet, causing arbitrary code execution.
Statement
To trigger this issue, the attacker must be on the local network, IPV6, and the parameter net.ipv6.conf must be enabled.[NIC].accept_ra enabled. By default, net.ipv6.conf.[NIC].accept_ra is disabled for Red Hat Enterprise Linux. In the default configuration, only local attacks are possible. The bug was introduced upstream by commit 3dec89b14d37 ("net/ipv6: Remove expired routes with a separated list of routes.").
Mitigation
The remote attack is potentially possible in the local network only. It is not possible if param
net.ipv6.conf.[NIC].accept_ra
disabled. Check this param value with the command
cat /proc/sys/net/ipv6/conf/default/accept_ra
or /proc/sys/net/ipv6/conf/eth0/accept_ra
(where eth0 is the name of the networking interface).
If you cannot run this or a similar command and parameter accept_ra is not available, then IPV6 is disabled.
If IPV6 is not being used, it is possible to disable it completely, and there is instruction on how to do this:
https://access.redhat.com/solutions/8709
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | 7.5 | 7.5 |
| Attack Vector | Adjacent Network | Adjacent Network | Adjacent Network |
| Attack Complexity | High | High | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When a race condition makes it possible to bypass a resource cleanup routine or trigger multiple initialization routines, it may lead to resource exhaustion.
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Instability
When a race condition allows multiple control flows to access a resource simultaneously, it might lead the product(s) into unexpected states, possibly resulting in a crash.
Confidentiality,Integrity
Technical Impact: Read Files or Directories; Read Application Data
When a race condition is combined with predictable resource names and loose permissions, it may be possible for an attacker to overwrite or access confidential data (CWE-59).
Access Control
Technical Impact: Execute Unauthorized Code or Commands; Gain Privileges or Assume Identity; Bypass Protection Mechanism
This can have security implications when the expected synchronization is in security-critical code, such as recording whether a user is authenticated or modifying important state information that should not be influenced by an outsider.
Acknowledgements
Red Hat would like to thank Lucas Leong (Trend Micro Zero Day Initiative) for reporting this issue.
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