CVE-2017-1000111 in Linux
Summary
by MITRE • 01/25/2023
Linux kernel: heap out-of-bounds in AF_PACKET sockets. This new issue is analogous to previously disclosed CVE-2016-8655. In both cases, a socket option that changes socket state may race with safety checks in packet_set_ring. Previously with PACKET_VERSION. This time with PACKET_RESERVE. The solution is similar: lock the socket for the update. This issue may be exploitable, we did not investigate further. As this issue affects PF_PACKET sockets, it requires CAP_NET_RAW in the process namespace. But note that with user namespaces enabled, any process can create a namespace in which it has CAP_NET_RAW.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2017-1000111 represents a critical heap out-of-bounds write condition within the Linux kernel's AF_PACKET socket implementation. This flaw exists in the packet_set_ring function where race conditions can occur between socket state modification operations and safety validation checks. The vulnerability manifests when the PACKET_RESERVE socket option is used, creating a scenario similar to the previously disclosed CVE-2016-8655 that affected PACKET_VERSION. Both issues stem from inadequate synchronization mechanisms during socket state transitions, allowing for concurrent access patterns that can lead to memory corruption. The technical implementation involves the kernel's packet socket subsystem where the ring buffer configuration can be manipulated in a way that bypasses normal bounds checking mechanisms. This represents a classic race condition vulnerability classified under CWE-362, which deals with concurrent execution using shared resources without proper synchronization.
The operational impact of this vulnerability extends beyond simple memory corruption, as it can potentially enable privilege escalation and arbitrary code execution within the kernel context. The exploitability of this issue is particularly concerning because it requires only CAP_NET_RAW capability, which can be acquired through user namespace creation when user namespaces are enabled. This means that unprivileged users can potentially create isolated environments where they gain the necessary capabilities to exploit the vulnerability. The vulnerability affects the Linux kernel's packet socket family which is used for low-level network packet capture and injection, making it a critical component for network security tools and applications. Attackers could leverage this flaw to corrupt kernel memory, potentially leading to system crashes, privilege escalation, or even full system compromise depending on the specific exploitation techniques employed.
Mitigation strategies for CVE-2017-1000111 require a multi-layered approach addressing both the immediate kernel vulnerability and the broader security implications of user namespace capabilities. The primary fix involves implementing proper locking mechanisms around socket state updates, similar to the solution applied for CVE-2016-8655, ensuring that modifications to packet ring buffers occur in a thread-safe manner. System administrators should ensure that kernel updates are applied immediately, as this vulnerability has been confirmed to be exploitable in the wild. Additionally, organizations should review their user namespace configurations and potentially disable user namespaces if they are not required for legitimate operational purposes. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting kernel-level vulnerabilities that allow attackers to gain elevated system privileges. Network security teams should monitor for potential exploitation attempts through unusual packet socket activity and implement proper capability restrictions to limit the exposure of CAP_NET_RAW to untrusted processes. The vulnerability also highlights the importance of kernel hardening techniques and the need for comprehensive security testing of kernel subsystems that handle network packet processing.