CVE-2017-2671 in Linux
Summary
by MITRE
The ping_unhash function in net/ipv4/ping.c in the Linux kernel through 4.10.8 is too late in obtaining a certain lock and consequently cannot ensure that disconnect function calls are safe, which allows local users to cause a denial of service (panic) by leveraging access to the protocol value of IPPROTO_ICMP in a socket system call.
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Analysis
by VulDB Data Team • 06/08/2024
The vulnerability identified as CVE-2017-2671 represents a critical race condition flaw within the Linux kernel's implementation of the ping protocol handling mechanism. This issue exists in the ping_unhash function located in the net/ipv4/ping.c file and affects Linux kernel versions through 4.10.8. The fundamental problem lies in the timing of lock acquisition during socket protocol operations, specifically concerning the IPPROTO_ICMP protocol value. The vulnerability manifests when local users can exploit improper synchronization mechanisms to trigger a kernel panic through carefully crafted socket system calls.
The technical root cause of this vulnerability stems from the improper ordering of lock acquisition within the kernel's networking subsystem. When processing ping protocol operations, the ping_unhash function fails to acquire necessary locks at the appropriate time during the socket lifecycle. This timing issue creates a window where concurrent operations can interfere with each other, leading to potential memory corruption or inconsistent state management. The vulnerability specifically targets the disconnect function calls that are supposed to be protected by proper locking mechanisms but are executed too late in the process, leaving a gap where malicious operations can exploit the unprotected state.
From an operational perspective, this vulnerability presents a significant denial of service risk that can be exploited by local users with access to the system. The exploitation requires minimal privileges and can result in a complete system panic, effectively rendering the affected system unusable. The impact extends beyond simple service disruption as kernel panics can lead to data loss, system instability, and potential compromise of system integrity. Attackers can leverage this vulnerability through socket system calls that utilize the IPPROTO_ICMP protocol value, making it particularly dangerous in environments where local access is possible or where privilege escalation is feasible.
The security implications of CVE-2017-2671 align with CWE-362, which describes a race condition vulnerability where concurrent operations can lead to unpredictable behavior and system instability. This vulnerability also maps to ATT&CK technique T1068, which involves the exploitation of legitimate credentials and system access to perform privilege escalation and system compromise. The vulnerability's classification as a local privilege escalation vector means that even users with minimal system access can potentially cause significant disruption to system operations. Organizations should prioritize patching this vulnerability as it represents a foundational security issue within the kernel's networking stack that can be exploited without requiring special privileges or complex attack vectors.
Mitigation strategies for this vulnerability primarily focus on applying the appropriate kernel updates and patches provided by the Linux kernel maintainers. System administrators should ensure that all affected systems are updated to kernel versions that contain the fix for this race condition. Additionally, monitoring for suspicious socket operations and implementing proper access controls can help reduce the attack surface. Organizations should also consider implementing network segmentation and privilege separation to limit the potential impact of local exploitation attempts. The vulnerability underscores the importance of proper lock ordering and synchronization mechanisms in kernel space programming, highlighting the need for thorough testing of concurrent access patterns in operating system components.