CVE-2018-10380 in KWallet
Summary
by MITRE
kwallet-pam in KDE KWallet before 5.12.6 allows local users to obtain ownership of arbitrary files via a symlink attack.
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Analysis
by VulDB Data Team • 02/03/2020
The vulnerability identified as CVE-2018-10380 affects the kwallet-pam component within KDE KWallet versions prior to 5.12.6, presenting a significant local privilege escalation risk through symbolic link manipulation. This flaw resides in the password authentication module implementation that handles wallet access controls and file system operations. The vulnerability enables attackers with local system access to exploit a race condition or insecure file handling mechanism that permits arbitrary file ownership acquisition through carefully crafted symbolic link attacks.
The technical implementation of this vulnerability stems from improper handling of file system operations within the pam module's wallet access routines. When kwallet-pam processes wallet authentication requests, it fails to properly validate or sanitize file paths that may contain symbolic links. An attacker can create malicious symbolic links in strategic locations where the pam module expects to find wallet files or temporary data structures, allowing them to manipulate file ownership and potentially gain elevated privileges. This type of attack typically involves exploiting a time-of-check to time-of-use vulnerability pattern where the module checks for file existence and permissions before performing operations that could be influenced by a malicious symlink.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a critical weakness in the authentication infrastructure of KDE desktop environments. Local users who can write to directories where kwallet-pam operates can manipulate the wallet file system to gain unauthorized access to sensitive data or elevate their privileges to the level of the wallet service. The attack vector requires local system access but does not require network connectivity or complex exploitation techniques, making it particularly dangerous in multi-user environments or when users have varying privilege levels. This vulnerability directly impacts the principle of least privilege and compromises the integrity of the authentication system.
Mitigation strategies for CVE-2018-10380 primarily focus on immediate patching of affected KDE KWallet installations to version 5.12.6 or later, which incorporates proper file path validation and symlink handling mechanisms. System administrators should also implement proper file system permissions and ensure that wallet-related directories are not writable by untrusted users. The vulnerability aligns with CWE-367, which describes Time-of-Check to Time-of-Use race conditions, and may map to ATT&CK technique T1068, which covers privilege escalation through local exploitation. Additional defensive measures include monitoring for suspicious symlink creation patterns in wallet-related directories and implementing mandatory access controls to limit the impact of potential exploitation. Organizations should also consider the broader context of PAM module security and ensure that all authentication components properly validate file system operations to prevent similar race condition vulnerabilities.