Overview
The Linux kernel, the core component of the Linux operating system, is the target of a serious vulnerability labelled as CVE-2024-0193. This vulnerability resides within the kernel’s netfilter subsystem, a framework that provides the tools necessary for the manipulation of network packets. It is a use-after-free flaw, which can allow an attacker to execute arbitrary code, potentially leading to system compromise or data leakage. This vulnerability is of particular concern as it can be exploited by a local unprivileged user with CAP_NET_ADMIN capability, thereby providing a straightforward path to escalating their privileges on the system.
Vulnerability Summary
CVE ID: CVE-2024-0193
Severity: High (7.8 CVSS)
Attack Vector: Local
Privileges Required: Low (CAP_NET_ADMIN)
User Interaction: None
Impact: Potential system compromise, data leakage
Affected Products
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Product | Affected Versions
Linux Kernel | Versions prior to patch release
How the Exploit Works
The vulnerability at its core is a use-after-free flaw. A use-after-free error occurs when a piece of memory is freed (deleted) while there are still pointers to it that haven’t been updated. In this case, the netfilter subsystem of the Linux kernel is affected. Specifically, if the catchall element is garbage-collected when the pipapo set is removed, the element can be deactivated twice. This can cause a use-after-free issue on an NFT_CHAIN object or NFT_OBJECT object, allowing a local unprivileged user with CAP_NET_ADMIN capability to escalate their privileges on the system.
Conceptual Example Code
Below is a conceptual representation of how the vulnerability might be exploited:
# Gain CAP_NET_ADMIN capability
sudo setcap cap_net_admin+ep /bin/bash
# Run command to interact with netfilter and trigger the use-after-free flaw
echo "remove pipapo set" | nft -f -This pseudo-code demonstrates the potential exploitation of the vulnerability by an unprivileged user gaining the CAP_NET_ADMIN capability and then running a command to interact with the netfilter subsystem in a way that triggers the use-after-free flaw. This could potentially allow the user to escalate their privileges and execute arbitrary code.
To mitigate this vulnerability, it is recommended to immediately apply any available vendor patches. In the absence of a patch, a Web Application Firewall (WAF) or Intrusion Detection System (IDS) could be used as a temporary mitigation measure. However, these should not be seen as a long-term solution, but rather a stopgap until patches can be applied.