CVE-2007-4998 in Linux
Summary
by MITRE
cp, when running with an option to preserve symlinks on multiple OSes, allows local, user-assisted attackers to overwrite arbitrary files via a symlink attack using crafted directories containing multiple source files that are copied to the same destination.
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Analysis
by VulDB Data Team • 11/06/2017
The vulnerability identified as CVE-2007-4998 affects the cp command across multiple operating systems when executed with options designed to preserve symbolic links. This flaw represents a critical security issue that enables local attackers with user-assisted privileges to perform unauthorized file overwrites through carefully crafted directory structures. The vulnerability stems from improper handling of symbolic links during file copying operations, creating a scenario where an attacker can manipulate the copy process to target arbitrary files within the system.
The technical implementation of this vulnerability exploits the cp command's behavior when processing multiple source files that contain symbolic links. When the command encounters a symlink during copy operations, it may follow the link and copy the target file instead of preserving the symbolic link itself. An attacker can create a directory structure containing multiple source files with symbolic links that point to sensitive system files or files owned by other users. When the cp command processes these directories with symlink preservation options, the copying mechanism can be manipulated to overwrite files that the attacker does not have direct write permissions to, effectively bypassing normal access controls.
The operational impact of this vulnerability extends beyond simple file overwrites to potentially enable privilege escalation and persistent system compromise. Attackers can leverage this flaw to overwrite critical system files, configuration files, or files belonging to other users, potentially leading to complete system compromise. The vulnerability is particularly dangerous in multi-user environments where attackers may target files owned by privileged users or system services. This issue affects multiple operating systems including various unix-like systems and linux distributions where the cp command implementation is vulnerable to symlink manipulation during copy operations.
Security professionals should note that this vulnerability aligns with CWE-59 and CWE-22 categories, representing a symlink attack that combines path traversal and file overwrite techniques. The attack pattern follows established methods described in the ATT&CK framework under technique T1059 for executing commands and potentially T1548 for privilege escalation. Organizations should implement immediate mitigations including updating system utilities to patched versions, implementing proper file permissions, and monitoring for suspicious file operations. The vulnerability demonstrates the importance of proper input validation and the dangers of symbolic link handling in file manipulation utilities, emphasizing the need for robust security practices in system command implementations.
Mitigation strategies should include upgrading to patched versions of coreutils where the cp command is implemented, implementing proper directory permissions to prevent unauthorized symlink creation, and monitoring copy operations for suspicious patterns. System administrators should also consider implementing file integrity monitoring solutions to detect unauthorized file modifications that could result from this vulnerability. The vulnerability highlights the critical need for proper sandboxing and access control mechanisms when executing file manipulation operations, particularly in environments where users may have limited privileges but can influence system operations through carefully crafted inputs.