CVE-2016-4477 in wpa_supplicant
Summary
by MITRE
wpa_supplicant 0.4.0 through 2.5 does not reject \n and \r characters in passphrase parameters, which allows local users to trigger arbitrary library loading and consequently gain privileges, or cause a denial of service (daemon outage), via a crafted (1) SET, (2) SET_CRED, or (3) SET_NETWORK command.
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Analysis
by VulDB Data Team • 08/17/2022
The vulnerability identified as CVE-2016-4477 affects wpa_supplicant versions 0.4.0 through 2.5 and represents a significant security flaw in wireless network authentication software. This issue stems from inadequate input validation within the command processing mechanism of the wpa_supplicant daemon, specifically concerning passphrase parameters that are used during wireless network authentication processes. The vulnerability enables local attackers to manipulate the authentication flow by injecting carriage return and line feed characters into passphrase values, creating a dangerous attack vector that can be exploited to compromise system integrity.
The technical flaw manifests in the improper handling of special characters within passphrase parameters, where the wpa_supplicant software fails to properly sanitize input data before processing commands. When attackers submit crafted SET, SET_CRED, or SET_NETWORK commands containing these problematic characters, the software processes them without adequate validation, leading to potential arbitrary library loading. This occurs because the command parsing mechanism does not properly escape or reject control characters that could alter the intended execution flow of the authentication process. The vulnerability is particularly concerning as it operates at the daemon level, allowing attackers to manipulate the core wireless authentication functionality.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential denial of service conditions that can severely disrupt wireless network connectivity. Local users who exploit this vulnerability can trigger arbitrary library loading, which may result in the execution of malicious code within the context of the wpa_supplicant daemon. This creates opportunities for privilege escalation attacks where attackers can gain elevated system privileges, potentially leading to complete system compromise. Additionally, the vulnerability can cause daemon outages that prevent legitimate wireless authentication attempts, effectively creating a denial of service condition that impacts network accessibility and user productivity.
Organizations should immediately update their wpa_supplicant implementations to versions that have addressed this vulnerability, as the affected versions remain susceptible to exploitation. The recommended mitigation strategy involves implementing proper input validation and sanitization mechanisms that reject or properly escape control characters within passphrase parameters. Security teams should also consider implementing monitoring solutions to detect unusual command sequences that might indicate exploitation attempts. This vulnerability aligns with CWE-170, which addresses improper handling of potentially dangerous input characters, and maps to ATT&CK technique T1068, which covers local privilege escalation through exploitation of software vulnerabilities. System administrators should also review and harden wireless network configurations to limit local access to wpa_supplicant interfaces and implement proper access controls to minimize the attack surface available to potential exploiters.