CVE-2003-0854 in wu-ftpd
Summary
by MITRE
ls in the fileutils or coreutils packages allows local users to consume a large amount of memory via a large -w value, which can be remotely exploited via applications that use ls, such as wu-ftpd.
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Analysis
by VulDB Data Team • 06/23/2024
The vulnerability described in CVE-2003-0854 represents a memory exhaustion flaw within the ls command utility that is part of the coreutils package suite. This issue manifests when the ls command processes a large -w parameter value, causing the application to allocate excessive memory resources. The vulnerability is particularly concerning because it can be remotely exploited through applications that invoke ls functionality, such as the wu-ftpd FTP server. The root cause stems from inadequate input validation and memory allocation handling within the ls command's argument processing logic.
The technical implementation of this vulnerability demonstrates a classic buffer over-allocation scenario where the ls command does not properly constrain the memory allocation based on user-provided -w values. When an attacker provides an excessively large width parameter, the command attempts to allocate memory proportional to this value, potentially consuming all available system memory. This behavior aligns with CWE-122, which describes insufficient checking of the size of input data leading to buffer overflows and memory exhaustion conditions. The vulnerability operates at the command-line interface level and can be triggered through various attack vectors including remote FTP connections that execute ls commands on behalf of users.
The operational impact of this vulnerability extends beyond simple resource exhaustion, creating potential denial-of-service conditions that can compromise system availability. When exploited successfully, the vulnerability can cause the targeted system to become unresponsive or crash entirely, as the memory allocation requests exceed available system resources. This makes it particularly dangerous in server environments where system uptime and availability are critical. The remote exploitation capability through wu-ftpd demonstrates how this vulnerability can be leveraged in real-world scenarios, where an attacker could remotely trigger the memory exhaustion condition by crafting malicious FTP commands that invoke ls with excessive parameters. The attack follows patterns consistent with ATT&CK technique T1499.004, which involves resource exhaustion through manipulation of system resources.
Mitigation strategies for this vulnerability should focus on input validation and parameter restriction within the ls command implementation. System administrators should ensure that all affected systems have received appropriate patches and updates from their respective distribution vendors. The recommended approach includes implementing strict bounds checking on all user-provided arguments, particularly those that control memory allocation parameters. Additionally, network-level firewalls and access controls should be configured to limit exposure to vulnerable applications, while monitoring systems should be deployed to detect unusual memory consumption patterns that might indicate exploitation attempts. Organizations should also consider implementing resource limits and process isolation to contain the impact of potential exploitation attempts, ensuring that even if the vulnerability is exploited, the system remains operational and available to legitimate users.