CVE-2003-0136 in LPRng
Summary
by MITRE
psbanner in the LPRng package allows local users to overwrite arbitrary files via a symbolic link attack on the /tmp/before file.
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Analysis
by VulDB Data Team • 09/05/2019
The vulnerability identified as CVE-2003-0136 resides within the LPRng package's psbanner utility, representing a classic symbolic link attack scenario that exploits insecure temporary file handling. This flaw specifically targets the /tmp/before file which serves as a temporary staging area during print job processing. The vulnerability stems from the utility's failure to properly validate or secure temporary file creation processes, creating an opportunity for local attackers to manipulate the system's file operations through malicious symbolic link placement.
This security weakness operates under the broader category of insecure temporary file handling as classified by CWE-377, where the system creates temporary files with predictable names and locations without adequate security measures. The psbanner utility in LPRng demonstrates poor privilege management and file access control when dealing with temporary files, allowing attackers to establish symbolic links in the /tmp directory that point to critical system files or configuration resources. The attack vector specifically leverages the fact that the utility does not perform proper validation of the temporary file's existence or ownership before writing to it, creating a window of opportunity for privilege escalation or data manipulation.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can potentially enable attackers to modify system-critical files, inject malicious content into print job processing workflows, or disrupt legitimate printing operations. Local users with access to the system can exploit this flaw to gain elevated privileges or compromise the integrity of print services, which may be particularly concerning in multi-user environments where print spooling services are actively utilized. The vulnerability affects systems running the LPRng package and demonstrates a fundamental lack of proper input validation and file system security practices in the utility's implementation.
Mitigation strategies for this vulnerability include implementing proper temporary file creation mechanisms that utilize secure file handling practices such as creating files with unique names and appropriate permissions, using the O_EXCL flag during file creation to prevent race conditions, and ensuring that temporary files are created in secure directories with restricted access permissions. System administrators should also consider implementing file system monitoring to detect unauthorized symbolic link creation in temporary directories and apply the principle of least privilege to reduce the potential impact of such attacks. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques through file system manipulation, highlighting the need for comprehensive system hardening and secure coding practices that prevent predictable temporary file creation patterns.