CVE-2003-0535 in Xbl
Summary
by MITRE
Buffer overflow in xbl 1.0k and earlier allows local users to gain privileges via a long -display command line option.
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Analysis
by VulDB Data Team • 05/01/2019
The vulnerability identified as CVE-2003-0535 represents a critical buffer overflow flaw in the xbl utility version 1.0k and earlier releases. This issue specifically manifests when processing command line arguments, particularly the -display option which is commonly used to specify X Window System display connections. The flaw occurs due to inadequate input validation and bounds checking within the argument parsing mechanism, allowing maliciously crafted input to overwrite adjacent memory locations in the program's execution space.
The technical implementation of this vulnerability stems from improper handling of command line parameters where the xbl utility fails to properly validate the length of the -display argument before copying it into a fixed-size buffer. This classic buffer overflow condition creates an opportunity for attackers to execute arbitrary code with elevated privileges, as the utility typically runs with higher permissions than regular user processes. The vulnerability is classified as a local privilege escalation vector since it requires physical access or execution privileges within the target system, but the impact extends to full system compromise when exploited successfully.
From an operational perspective, this vulnerability presents significant risks to systems running affected versions of xbl, particularly in multi-user environments where local access might be obtained through various attack vectors. The exploitability of this flaw increases when the utility is setuid root or when it runs with elevated privileges, as the buffer overflow can be leveraged to execute malicious code with system-level privileges. This vulnerability directly relates to CWE-121, which describes stack-based buffer overflow conditions, and aligns with ATT&CK technique T1068, which covers privilege escalation through local exploits.
Security professionals should prioritize immediate remediation of this vulnerability through patching or upgrading to versions of xbl that contain proper input validation and bounds checking mechanisms. System administrators should also implement monitoring for unusual command line argument patterns and consider restricting execution privileges for the xbl utility where possible. Additional mitigations include implementing address space layout randomization and stack canaries to make exploitation more difficult, though these measures do not eliminate the underlying vulnerability. The most effective long-term solution involves upgrading to patched versions that properly validate all input parameters and implement secure coding practices to prevent similar buffer overflow conditions in future releases.