CVE-2006-7094 in ftpd
Summary
by MITRE
ftpd, as used by Gentoo and Debian Linux, sets the gid to the effective uid instead of the effective group id before executing /bin/ls, which allows remote authenticated users to list arbitrary directories with the privileges of gid 0 and possibly enable additional attack vectors.
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Analysis
by VulDB Data Team • 10/10/2017
The vulnerability identified as CVE-2006-7094 affects ftpd implementations used in Gentoo and Debian Linux distributions, representing a critical privilege escalation flaw in the file transfer protocol daemon. This issue stems from a fundamental error in the permission handling mechanism where the daemon incorrectly sets the group identifier to the effective user id rather than the effective group id during execution of the /bin/ls command. The flaw occurs specifically within the context of remote authenticated users who have established connections to the FTP service, creating a scenario where legitimate access can be exploited for malicious purposes.
The technical implementation of this vulnerability lies in the improper handling of process credentials during command execution. When ftpd executes /bin/ls to list directory contents, it fails to correctly establish the group privileges, instead inadvertently setting the group id to match the user id value. This misconfiguration allows authenticated attackers to leverage the compromised privilege structure to access directories that would normally require root group permissions, effectively elevating their privileges within the system's file access controls. The vulnerability operates under the principle of privilege confusion where the system's permission model becomes compromised due to incorrect credential assignment.
From an operational standpoint, this vulnerability creates significant security implications for systems running affected ftpd implementations. Remote authenticated users can exploit this flaw to enumerate directory structures that should be restricted to root or administrative group access, potentially exposing sensitive system files, configuration data, and other privileged resources. The impact extends beyond simple directory listing as the elevated privileges could enable attackers to identify system weaknesses, locate potential targets for further exploitation, and establish persistent access vectors. This vulnerability directly aligns with attack patterns described in the attack tree methodology where privilege escalation serves as a foundational step for more complex compromise scenarios.
The security implications of this vulnerability extend to several industry standards and frameworks, particularly those addressing privilege management and credential handling. This flaw corresponds to CWE-250, which covers "Execute Code with Unusual or Unconventional Privilege Level," as the daemon executes commands with incorrect privilege levels. Additionally, the vulnerability relates to CWE-269, "Improper Privilege Management," since the system fails to properly manage and enforce group-based access controls during command execution. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques where adversaries leverage misconfigurations in system services to gain elevated permissions, specifically targeting the T1068 technique for local privilege escalation through service exploitation.
Mitigation strategies for CVE-2006-7094 require immediate attention from system administrators and security teams responsible for maintaining ftpd services on affected Linux distributions. The primary remediation involves updating the ftpd implementation to correctly handle group identifier assignments, ensuring that effective group id values are properly set before executing commands like /bin/ls. Organizations should implement comprehensive patch management procedures to address this vulnerability across all affected systems, particularly those running Gentoo or Debian-based distributions. Additionally, network segmentation and access control measures should be strengthened to limit the exposure of FTP services to unauthorized users, while monitoring systems should be deployed to detect potential exploitation attempts. The vulnerability also underscores the importance of regular security audits and code reviews focusing on privilege management and credential handling within system services, as similar misconfigurations could exist in other components of the operating system.