CVE-2003-0793 in GDM
Summary
by MITRE
GDM 2.4.4.x before 2.4.4.4, and 2.4.1.x before 2.4.1.7, does not restrict the size of input, which allows attackers to cause a denial of service (memory consumption).
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Analysis
by VulDB Data Team • 03/09/2021
The vulnerability identified as CVE-2003-0793 affects the GNOME Display Manager GDM version 2.4.4.x prior to 2.4.4.4 and 2.4.1.x prior to 2.4.1.7. This issue represents a classic buffer overflow condition that occurs when the system fails to properly validate input size limits during processing. The flaw exists in the input handling mechanisms of GDM, which is responsible for managing graphical login sessions in GNOME desktop environments. When an attacker provides input that exceeds the expected size parameters, the system processes this oversized data without proper bounds checking, leading to excessive memory allocation and consumption.
This vulnerability operates under the Common Weakness Enumeration CWE-121 category, which encompasses weaknesses related to buffer overflow conditions. The specific implementation flaw occurs in the input validation routines where the system does not enforce maximum size constraints on user-provided data. The operational impact of this vulnerability manifests as a denial of service condition that consumes system memory resources, potentially leading to system instability or complete service unavailability. Attackers can exploit this weakness by submitting intentionally oversized input parameters to the GDM service, causing the system to allocate increasingly larger memory blocks until system resources are exhausted.
The attack vector leverages the lack of proper input sanitization within the display manager's processing pipeline, making it particularly dangerous in environments where GDM serves as the primary authentication interface. This weakness aligns with ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion. The vulnerability is particularly concerning because it affects the foundational authentication layer of the desktop environment, potentially allowing attackers to disrupt legitimate user access to the system. The memory consumption pattern typically follows a predictable escalation where each malicious input request causes progressive memory allocation until the system reaches its resource limits.
Mitigation strategies for this vulnerability include applying the vendor-provided patches that implement proper input size validation and bounds checking within the GDM component. System administrators should prioritize updating to GDM versions 2.4.4.4 or 2.4.1.7 and later, which contain the necessary fixes for this memory consumption issue. Additional protective measures include implementing network-level controls to restrict access to the GDM service, monitoring for unusual memory consumption patterns, and establishing proper input validation policies at multiple layers of the authentication stack. The fix typically involves implementing maximum input length constraints and ensuring that all user-provided data is validated against predetermined size limits before processing. Organizations should also consider implementing intrusion detection systems that can identify patterns consistent with this type of resource exhaustion attack, as well as maintaining regular vulnerability assessments to identify similar weaknesses in other system components.