CVE-2004-0564 in pppoe
Summary
by MITRE
Roaring Penguin pppoe (rp-ppoe), if installed or configured to run setuid root contrary to its design, allows local users to overwrite arbitrary files. NOTE: the developer has publicly disputed the claim that this is a vulnerability because pppoe "is NOT designed to run setuid-root." Therefore this identifier applies *only* to those configurations and installations under which pppoe is run setuid root despite the developer s warnings.
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Analysis
by VulDB Data Team • 06/02/2019
The vulnerability described in CVE-2004-0564 pertains to the Roaring Penguin pppoe daemon, a network connection utility designed for point-to-point protocol over ethernet connections. This specific flaw manifests when the application is incorrectly configured to operate with elevated privileges through setuid root permissions, despite the software developer's explicit design intention that it should not run with such privileges. The vulnerability represents a classic privilege escalation issue that occurs in misconfigured environments where security best practices have been disregarded.
The technical flaw in rp-ppoe stems from its improper handling of file operations when executed with root privileges. When configured to run setuid root, local users can exploit a file overwrite vulnerability that allows them to manipulate arbitrary files on the system. This occurs because the application does not properly validate file paths or implement adequate access controls when performing file operations, creating a path traversal or file overwrite condition that can be leveraged by unauthorized users. The vulnerability essentially allows a local attacker to bypass normal file system permissions and modify critical system files, potentially leading to complete system compromise.
The operational impact of this vulnerability is significant within environments where pppoe is incorrectly configured to run with setuid root permissions. Attackers can exploit this weakness to overwrite system binaries, configuration files, or other critical resources, potentially leading to privilege escalation, system instability, or complete system takeover. The vulnerability demonstrates poor security design principles and highlights the importance of proper privilege management in network utilities. From an operational security perspective, this represents a critical configuration error that could be exploited by both malicious insiders and external attackers who gain local access to the system.
The root cause of this issue aligns with CWE-276, which describes inadequate file permissions and improper access control mechanisms. The vulnerability also relates to ATT&CK technique T1548.001, which covers privilege escalation through setuid binaries, and T1068, which involves local privilege escalation through exploitation of system vulnerabilities. Organizations should ensure that network utilities like pppoe are properly configured to run with minimal required privileges, following the principle of least privilege. The recommended mitigation involves removing setuid permissions from the pppoe binary and ensuring proper configuration management to prevent accidental privilege escalation. Additionally, system administrators should implement regular security audits to identify and correct such misconfigurations, as the vulnerability only manifests in non-standard installation scenarios that violate the software's intended security model.