CVE-2011-0988 in Linux
Summary
by MITRE
pure-ftpd 1.0.22, as used in SUSE Linux Enterprise Server 10 SP3 and SP4, and Enterprise Desktop 10 SP3 and SP4, when running OES Netware extensions, creates a world-writeable directory, which allows local users to overwrite arbitrary files and gain privileges via unspecified vectors.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 02/02/2025
The vulnerability identified as CVE-2011-0988 affects pure-ftpd version 1.0.22 when deployed on SUSE Linux Enterprise Server and Desktop platforms with OES Netware extensions enabled. This represents a critical privilege escalation vulnerability that stems from improper directory permissions during the FTP service operation. The flaw specifically manifests when the pure-ftpd daemon creates directories with world-writable permissions, creating an exploitable condition that enables local attackers to manipulate system files and potentially escalate their privileges to root level access.
The technical root cause of this vulnerability lies in the improper handling of directory creation permissions within the pure-ftpd implementation when operating in OES Netware extension mode. When the FTP daemon initializes or processes certain commands, it generates directories with permissions that allow any local user to write to them. This misconfiguration creates a path traversal and file overwriting opportunity that can be leveraged to replace critical system binaries or configuration files with malicious equivalents. The vulnerability operates under CWE-732: Incorrect Permission Assignment for Critical Resource, which specifically addresses situations where system resources receive overly permissive access controls.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities to encompass full system compromise potential. Local attackers can exploit this condition to substitute legitimate system binaries with backdoor versions, modify system configuration files, or create malicious scripts that persist across system reboots. The attack vector typically involves identifying the world-writable directory created by pure-ftpd, crafting malicious payloads that can be executed with elevated privileges, and then leveraging the overwritten files to gain persistent access. This vulnerability directly maps to ATT&CK technique T1068: Exploitation for Privilege Escalation, where adversaries exploit software vulnerabilities to elevate their access rights.
Mitigation strategies for CVE-2011-0988 require immediate system hardening measures including updating to patched versions of pure-ftpd, implementing proper directory permission controls, and disabling unnecessary OES Netware extensions when not required. System administrators should conduct thorough permission audits of FTP-related directories and ensure that no world-writable directories exist in the system path. The recommended approach includes upgrading to pure-ftpd version 1.0.23 or later, which contains the necessary patches to address the improper permission assignment issue. Additionally, implementing network segmentation and access controls can limit the potential impact of exploitation attempts, while regular security scanning should identify similar permission misconfigurations across the enterprise infrastructure. Organizations should also consider implementing privilege separation techniques and monitoring for suspicious file modification patterns that could indicate exploitation attempts.