CVE-2008-3525 in Linux
Summary
by MITRE
The sbni_ioctl function in drivers/net/wan/sbni.c in the wan subsystem in the Linux kernel 2.6.26.3 does not check for the CAP_NET_ADMIN capability before processing a (1) SIOCDEVRESINSTATS, (2) SIOCDEVSHWSTATE, (3) SIOCDEVENSLAVE, or (4) SIOCDEVEMANSIPATE ioctl request, which allows local users to bypass intended capability restrictions.
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Analysis
by VulDB Data Team • 08/17/2019
The vulnerability identified as CVE-2008-3525 resides within the Linux kernel's wan subsystem, specifically in the sbni_ioctl function located at drivers/net/wan/sbni.c. This flaw represents a significant capability bypass issue that affects kernel versions up to 2.6.26.3, creating a dangerous privilege escalation vector for local attackers. The vulnerability manifests through four distinct ioctl commands that should require the CAP_NET_ADMIN capability for proper execution but instead execute without any capability checks, allowing unauthorized users to perform network administrative operations.
The technical implementation of this vulnerability stems from inadequate input validation within the kernel's network subsystem. When local users execute the SIOCDEVRESINSTATS, SIOCDEVSHWSTATE, SIOCDEVENSLAVE, or SIOCDEVEMANSIPATE ioctl requests, the sbni_ioctl function fails to verify whether the calling process possesses the necessary network administration privileges. This oversight creates a direct pathway for privilege escalation, as these ioctl operations typically require elevated permissions to modify network device configurations and statistics. The absence of capability checks means that any local user can potentially invoke these administrative functions, effectively bypassing the kernel's security model designed to restrict such operations to privileged processes.
From an operational perspective, this vulnerability poses a substantial risk to system integrity and network security. Local attackers can exploit this flaw to manipulate network device states, potentially disrupting network services or creating backdoors within the system. The impact extends beyond simple privilege escalation, as these operations can affect network connectivity, device enumeration, and hardware state management. The vulnerability particularly affects systems running kernel versions up to 2.6.26.3, where the lack of proper capability enforcement creates a persistent security weakness that could be leveraged for more sophisticated attacks.
The vulnerability aligns with CWE-276, which describes inadequate privilege management, and represents a clear violation of the principle of least privilege. According to ATT&CK framework, this issue maps to T1068, privilege escalation, and T1566, credential harvesting, as local users can effectively gain unauthorized administrative access. The security implications extend to potential information disclosure through device statistics manipulation and service disruption through hardware state modification. Organizations should prioritize patching affected systems and implementing proper monitoring to detect unauthorized ioctl operations within the wan subsystem, particularly in environments where local user access is not strictly controlled. This vulnerability underscores the critical importance of capability checks in kernel space operations and demonstrates how seemingly minor oversight in privilege validation can create significant security exposure points.