CVE-2007-5194 in rMake
Summary
by MITRE
The Chroot server in rMake 1.0.11 creates a /dev/zero device file with read/write permissions for the rMake user and the same minor device number as /dev/port, which might allow local users to gain root privileges.
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Analysis
by VulDB Data Team • 09/09/2018
The vulnerability identified as CVE-2007-5194 resides within the chroot server implementation of rMake version 1.0.11, presenting a significant privilege escalation risk for local attackers. This flaw stems from improper device file creation during the chroot process, specifically involving the /dev/zero device file that is crafted with incorrect permissions and device number associations. The vulnerability represents a classic case of insecure temporary file creation and device file handling that can be exploited to bypass security boundaries established by the chroot mechanism.
The technical flaw manifests when the chroot server creates a /dev/zero device file with read/write permissions specifically granted to the rMake user account, while simultaneously assigning it the identical minor device number as /dev/port. This duplication creates a critical conflict in the device file system where the rMake user can manipulate the /dev/zero file to gain access to the underlying /dev/port device, which typically requires root privileges to access. The minor device number serves as the critical identifier that allows the attacker to exploit the device file mapping, as it directly corresponds to the port I/O device that provides low-level hardware access capabilities. This issue aligns with CWE-362, which addresses concurrent execution using shared resource vulnerabilities, and CWE-276, concerning improper file permissions.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it allows local users to effectively bypass the security model that chroot is designed to provide. When an attacker successfully exploits this vulnerability, they can leverage the access to /dev/port to perform operations that would normally require root privileges, including direct hardware access and potential system compromise. The exploitation process typically involves the attacker creating a malicious device file that maps to the same minor device number as /dev/port, then using the rMake user's access to /dev/zero to manipulate the device file system. This vulnerability is particularly dangerous because it undermines the fundamental security principle that chroot environments should isolate processes from the rest of the system, making it a prime target for attackers seeking to escalate privileges within a compromised system.
Mitigation strategies for CVE-2007-5194 should focus on immediate patching of the rMake software to version 1.0.12 or later, which contains the necessary fixes to properly handle device file creation and permissions. System administrators should also implement monitoring of device file creation within chroot environments and establish strict permissions for device files, particularly ensuring that device files do not share minor device numbers with privileged devices. The implementation of proper device file validation and the enforcement of least privilege principles for chroot environments can significantly reduce the risk of exploitation. Additionally, organizations should consider implementing the principle of least privilege for user accounts running chroot processes and ensure that all device files created within chroot environments are properly validated against system device mappings. This vulnerability demonstrates the importance of device file management in security contexts and aligns with ATT&CK techniques related to privilege escalation through exploitation of system vulnerabilities, specifically T1068 which covers local privilege escalation.