CVE-2017-9077 in Linux
Summary
by MITRE
The tcp_v6_syn_recv_sock function in net/ipv6/tcp_ipv6.c in the Linux kernel through 4.11.1 mishandles inheritance, which allows local users to cause a denial of service or possibly have unspecified other impact via crafted system calls, a related issue to CVE-2017-8890.
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Analysis
by VulDB Data Team • 12/06/2022
The tcp_v6_syn_recv_sock function in the Linux kernel version 4.11.1 contains a critical inheritance handling flaw that affects IPv6 TCP socket operations. This vulnerability resides in the net/ipv6/tcp_ipv6.c source file and represents a significant security weakness that can be exploited by local attackers to disrupt system operations. The flaw specifically manifests during the handling of TCP SYN_RECV sockets in IPv6 environments, where improper inheritance mechanisms lead to unpredictable behavior in socket state management. The vulnerability is particularly concerning because it allows attackers to craft specific system calls that can trigger the problematic code path, potentially leading to system instability or more severe consequences.
The technical nature of this vulnerability stems from how the kernel manages socket inheritance during the TCP handshake process in IPv6 networking. When a TCP connection enters the SYN_RECV state, the kernel must properly inherit certain socket parameters from the listening socket to the newly created connection socket. The flaw occurs in the tcp_v6_syn_recv_sock function where the inheritance process fails to correctly handle specific socket attributes, leading to memory corruption or invalid state transitions. This improper handling creates a condition where crafted system calls can cause the kernel to process socket parameters incorrectly, potentially resulting in null pointer dereferences or memory access violations that crash the kernel or create exploitable conditions.
From an operational perspective, this vulnerability presents a serious risk to Linux systems running kernel versions through 4.11.1, particularly those that handle substantial IPv6 traffic or operate in environments where local privilege escalation is a concern. The denial of service impact can render systems unusable by causing kernel panics or forcing system reboots, while the unspecified other impacts suggest potential for more sophisticated exploitation scenarios. Attackers with local access can leverage this vulnerability to disrupt services, potentially causing cascading failures in network infrastructure that relies on stable TCP connections. The vulnerability's relationship to CVE-2017-8890 indicates it shares similar underlying causes related to TCP socket inheritance mechanisms, suggesting a broader class of issues affecting kernel networking code.
Security mitigations for this vulnerability primarily involve upgrading to kernel versions that contain the appropriate patches, specifically those beyond version 4.11.1 where the inheritance handling has been corrected. System administrators should prioritize patching affected systems as a critical security measure, particularly in environments where IPv6 networking is actively used. Additionally, monitoring for unusual system behavior or kernel crashes that could indicate exploitation attempts should be implemented. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and relates to ATT&CK techniques involving privilege escalation and denial of service operations. Organizations should also consider implementing network segmentation and access controls to limit local user privileges, reducing the potential impact of local exploitation attempts. Regular security audits of kernel configurations and network services can help identify systems that may be vulnerable to this and similar TCP socket inheritance flaws.