CVE-2017-15868 in Linux
Summary
by MITRE • 01/25/2023
The bnep_add_connection function in net/bluetooth/bnep/core.c in the Linux kernel before 3.19 does not ensure that an l2cap socket is available, which allows local users to gain privileges via a crafted application.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2017-15868 resides within the Bluetooth Network Encapsulation Protocol (BNEP) implementation of the Linux kernel, specifically in the bnep_add_connection function located in net/bluetooth/bnep/core.c. This flaw represents a critical privilege escalation vulnerability that affects Linux kernel versions prior to 3.19, creating a pathway for local attackers to elevate their privileges from standard user level to root access. The issue stems from insufficient validation mechanisms within the Bluetooth networking stack that processes BNEP connections, allowing malicious applications to exploit a race condition or improper resource management during connection establishment. The vulnerability manifests when the kernel fails to properly verify the availability and integrity of underlying L2CAP (Logical Link Control and Adaptation Protocol) sockets before proceeding with BNEP connection initialization, creating a window of opportunity for privilege escalation attacks.
The technical exploitation of this vulnerability occurs through a carefully crafted application that manipulates the Bluetooth networking subsystem to trigger the flawed bnep_add_connection function. When a local user executes such an application, the kernel's insufficient socket validation allows the attacker to manipulate memory structures or leverage improper access controls within the Bluetooth subsystem. This particular flaw aligns with CWE-362, which describes a race condition vulnerability, and represents a classic example of improper privilege management where insufficient checks allow unauthorized elevation of privileges. The underlying mechanism involves the kernel's failure to properly validate that required L2CAP socket resources are available and properly initialized before proceeding with BNEP connection establishment, enabling attackers to potentially manipulate kernel memory or bypass security controls that should normally prevent privilege escalation.
From an operational impact perspective, this vulnerability poses significant risks to systems running affected Linux kernel versions, particularly those with Bluetooth capabilities enabled. The local privilege escalation opportunity means that any user with access to execute applications on the system can potentially gain root access, compromising the entire system's security posture. This vulnerability affects a wide range of devices including servers, desktops, and embedded systems that utilize Bluetooth networking features, making it particularly dangerous in enterprise environments where multiple users may have access to systems. The attack vector is relatively simple, requiring only local execution capability, which makes it difficult to detect and prevent through network-based security measures. Organizations with outdated kernel versions are particularly vulnerable, as the vulnerability has existed for years and affects systems that have not received proper security updates.
The mitigation strategies for CVE-2017-15868 primarily focus on kernel version updates, with the most effective solution being the deployment of Linux kernel versions 3.19 and later where the vulnerability has been patched. System administrators should prioritize updating all affected systems to ensure proper socket validation mechanisms are in place within the Bluetooth networking subsystem. Additionally, implementing proper access controls and monitoring for unusual Bluetooth activity can help detect potential exploitation attempts. Security configurations should include disabling Bluetooth functionality when not required, as this reduces the attack surface for this and similar vulnerabilities. Organizations should also implement regular security patch management processes to ensure timely deployment of kernel updates and maintain awareness of other potential vulnerabilities within the Bluetooth networking stack. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically leveraging kernel vulnerabilities to gain elevated system privileges, making it a critical target for both defensive and offensive security teams to understand and mitigate effectively.