CVE-2019-17052 in Linux
Summary
by MITRE
ax25_create in net/ax25/af_ax25.c in the AF_AX25 network module in the Linux kernel through 5.3.2 does not enforce CAP_NET_RAW, which means that unprivileged users can create a raw socket, aka CID-0614e2b73768.
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Analysis
by VulDB Data Team • 12/29/2023
The vulnerability identified as CVE-2019-17052 resides within the Linux kernel's AX.25 network module, specifically in the ax25_create function located in net/ax25/af_ax25.c. This flaw represents a critical privilege escalation issue that allows unprivileged users to bypass kernel security controls intended to restrict raw socket creation. The AX.25 protocol is a network protocol designed for amateur radio packet radio networks, but its implementation within the Linux kernel presents a significant security risk when proper privilege checks are omitted. The vulnerability affects all Linux kernel versions through 5.3.2, making it a widespread concern across numerous system deployments.
The technical flaw stems from the ax25_create function's failure to properly enforce the CAP_NET_RAW capability check during raw socket creation operations. In standard Linux security model, the CAP_NET_RAW capability is required to create raw sockets, which are network sockets that can send and receive packets at the network layer without protocol-specific processing. This capability is typically restricted to privileged processes or users with appropriate capabilities, as raw sockets can be used to craft and transmit arbitrary network packets, potentially enabling network reconnaissance, injection attacks, or other malicious activities. The absence of this capability check means that any unprivileged user can create raw AX.25 sockets, effectively circumventing the kernel's security controls designed to prevent unauthorized network packet manipulation.
The operational impact of this vulnerability is substantial, as it enables local privilege escalation and potential network-level attacks. An unprivileged user can exploit this flaw to create raw sockets that can be used to send and receive network packets at the AX.25 protocol layer, potentially allowing for network reconnaissance, packet injection, or even network disruption. The vulnerability could be particularly dangerous in environments where amateur radio networks are integrated with standard network infrastructure, as it could enable attackers to bypass network security controls and potentially gain unauthorized access to network resources. From an attack perspective, this vulnerability aligns with the ATT&CK technique T1068 for local privilege escalation and could be leveraged as part of broader attack chains involving network reconnaissance and lateral movement.
The security implications extend beyond simple privilege escalation, as this vulnerability can be exploited to perform network-level operations that should normally be restricted to privileged processes. Network administrators and security professionals should be particularly concerned about systems running affected kernel versions, as this vulnerability could enable attackers to perform activities such as crafting custom AX.25 frames, monitoring network traffic, or potentially disrupting amateur radio communications. The vulnerability's classification under CWE-276 indicates a problem with improper privileges or access control, specifically related to insufficient checks for required capabilities. Organizations should immediately apply kernel updates to address this vulnerability and consider implementing additional monitoring for suspicious raw socket creation activities. The flaw demonstrates the importance of proper capability enforcement in kernel modules and highlights the critical need for comprehensive security reviews of network protocol implementations.