CVE-2012-6704 in Linux
Summary
by MITRE • 01/25/2023
The sock_setsockopt function in net/core/sock.c in the Linux kernel before 3.5 mishandles negative values of sk_sndbuf and sk_rcvbuf, which allows local users to cause a denial of service (memory corruption and system crash) or possibly have unspecified other impact by leveraging the CAP_NET_ADMIN capability for a crafted setsockopt system call with the (1) SO_SNDBUF or (2) SO_RCVBUF option.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2012-6704 represents a critical flaw in the Linux kernel's socket implementation that affects versions prior to 3.5. This issue resides within the sock_setsockopt function located in net/core/sock.c, which handles socket option configuration operations. The vulnerability specifically targets the manipulation of socket send and receive buffer sizes through the SO_SNDBUF and SO_RCVBUF options, creating a scenario where negative buffer size values can be improperly processed. The flaw is particularly dangerous because it requires only the CAP_NET_ADMIN capability, which is commonly granted to network administrators and certain system processes, making exploitation relatively accessible within compromised environments.
The technical exploitation of this vulnerability occurs when a local attacker with CAP_NET_ADMIN privileges crafts a malicious setsockopt system call that passes negative integer values to the socket buffer size parameters. The kernel's socket implementation fails to properly validate these negative values, leading to unpredictable behavior in memory management operations. When the kernel attempts to process these invalid buffer size parameters, it can cause memory corruption within the socket buffer allocation mechanisms, ultimately resulting in system crashes or potentially more severe memory corruption that could be exploited for privilege escalation. The improper handling of negative buffer sizes creates arithmetic underflows and invalid memory access patterns that bypass normal kernel validation checks.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as demonstrated by the potential for unspecified other impacts mentioned in the CVE description. While the primary effect manifests as system crashes and memory corruption, the underlying flaw in buffer size validation could potentially be leveraged for more sophisticated attacks depending on the specific memory layout and system configuration. The vulnerability affects the fundamental socket communication mechanisms that underpin network services across Linux systems, making it a critical target for exploitation. Systems running affected kernel versions are particularly vulnerable during periods of high network activity when socket buffer management is most active, as the likelihood of triggering the corrupted state increases.
Mitigation strategies for CVE-2012-6704 require immediate kernel version upgrades to 3.5 or later, which contain the necessary patches to properly validate socket buffer size parameters and prevent negative values from being processed. Organizations should also implement monitoring for unauthorized use of the CAP_NET_ADMIN capability and conduct regular security audits to identify processes that may be leveraging this privilege unnecessarily. The vulnerability aligns with CWE-129, which addresses improper validation of input ranges, and can be categorized under ATT&CK technique T1068 for local privilege escalation through kernel exploits. System administrators should also consider implementing additional security controls such as mandatory access controls and privilege separation mechanisms to limit the scope of potential exploitation, particularly in environments where multiple users have access to network administration capabilities.