CVE-2003-0335 in Linux
Summary
by MITRE
rc.M in Slackware 9.0 calls quotacheck with the -M option, which causes the filesystem to be remounted and possibly reset security-relevant mount flags such as nosuid, nodev, and noexec.
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Analysis
by VulDB Data Team • 06/28/2021
The vulnerability described in CVE-2003-0335 represents a critical security flaw in the Slackware 9.0 operating system's initialization process. This issue resides within the rc.M script which is executed during system boot to manage filesystem mounting operations. The problem manifests when the quotacheck utility is invoked with the -M option, a command that fundamentally alters how filesystems are handled during the boot sequence. This particular implementation flaw creates an unintended consequence where the filesystem undergoes a remount operation that strips away essential security protections that have been carefully configured by system administrators.
The technical root cause of this vulnerability lies in the improper handling of mount flags during the quotacheck process. When the -M option is used, it forces the filesystem to be remounted with different parameters than originally intended. This remount operation specifically targets and removes security-relevant mount options including nosuid which prevents execution of setuid programs, nodev which disables device file interpretation, and noexec which prevents execution of binaries from the filesystem. These mount flags form the foundation of Linux filesystem security by creating layered protections against privilege escalation attacks and malicious code execution. The vulnerability essentially undermines these fundamental security controls by resetting them to default values without proper consideration of their security implications.
The operational impact of this vulnerability extends beyond simple filesystem access control, creating potential pathways for privilege escalation and system compromise. When security-relevant mount flags are removed during the boot process, attackers who gain access to the system could exploit the weakened filesystem protections to execute malicious code with elevated privileges. This vulnerability particularly affects systems where administrators have intentionally configured these mount options to prevent unauthorized access to sensitive system resources. The issue is especially concerning because it occurs during the system boot process when the system is most vulnerable and when security controls are being established. The remount operation essentially creates a window of opportunity for attackers to exploit the temporary loss of security protections while the system is initializing its filesystem components.
This vulnerability aligns with CWE-276, which addresses improper file permissions and access control, and specifically relates to improper privilege management during system initialization. From an ATT&CK framework perspective, this flaw maps to T1068, privilege escalation through exploitation of system initialization processes, and T1059, the execution of malicious code through compromised system services. The remediation strategy involves modifying the rc.M script to avoid using the -M option with quotacheck or implementing additional security measures that preserve mount flags during the filesystem check process. System administrators should also consider implementing additional monitoring to detect unauthorized changes to mount flags and ensure that security configurations remain intact throughout the boot process. The vulnerability demonstrates the critical importance of maintaining security controls during system initialization and highlights the need for careful consideration of all command-line options that may inadvertently compromise system security.