CVE-2019-9414 in Android
Summary
by MITRE
In wpa_supplicant, there is a possible man in the middle vulnerability due to improper input validation of the basicConstraints field of intermediary certificates. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation. Product: AndroidVersions: Android-10Android ID: A-111893041
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2019-9414 represents a critical security flaw in wpa_supplicant, the widely used wireless network authentication daemon that handles IEEE 802.11 authentication and key management. This issue manifests as a man-in-the-middle vulnerability that specifically targets the validation of certificate basicConstraints fields within intermediary certificates. The flaw occurs when the wpa_supplicant implementation fails to properly validate the basicConstraints extension in certificate chains, allowing malicious actors to potentially bypass certificate validation mechanisms. This vulnerability affects Android 10 systems and is particularly concerning because it operates without requiring any user interaction or additional execution privileges, making it highly exploitable in automated attack scenarios. The Android ID A-111893041 specifically tracks this vulnerability within Google's security tracking system, indicating its significance in the mobile security landscape.
The technical root cause of this vulnerability stems from improper input validation within the certificate processing logic of wpa_supplicant. When intermediary certificates are processed during the 802.11 authentication process, the system should rigorously validate the basicConstraints field to ensure proper certificate hierarchy and prevent unauthorized certificate delegation. However, the implementation fails to adequately enforce these validation checks, allowing certificates with malformed or improperly configured basicConstraints fields to be accepted as valid intermediaries in the certificate chain. This weakness directly relates to CWE-295, which covers improper certificate validation, and specifically addresses the failure to properly validate certificate path constraints. The vulnerability operates at the network protocol level, specifically within the IEEE 802.11 authentication framework where certificates are used to establish trust between wireless clients and access points.
The operational impact of CVE-2019-9414 extends beyond simple information disclosure to potentially enable full man-in-the-middle attacks within wireless networks. An attacker positioned within network range could exploit this vulnerability to intercept, modify, or redirect wireless traffic between legitimate clients and access points. The lack of user interaction requirements means that exploitation can occur automatically, making this vulnerability particularly dangerous in public or shared wireless environments. Attackers could potentially establish fake access points that appear legitimate to vulnerable devices, allowing them to capture sensitive information transmitted over the wireless network. This vulnerability specifically targets the trust establishment phase of wireless authentication, undermining the fundamental security guarantees provided by WPA2 and WPA3 protocols. The implications are severe as it can lead to complete network compromise, credential theft, and unauthorized access to corporate or personal data transmitted over wireless connections.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The primary solution involves updating wpa_supplicant to versions that properly validate certificate basicConstraints fields and implement robust certificate chain validation. Organizations should prioritize immediate deployment of security patches provided by Android vendors and device manufacturers. Network administrators should also consider implementing additional monitoring for suspicious wireless network activity and certificate validation failures. The fix should include enhanced validation routines that strictly enforce the basicConstraints extension requirements, ensuring that intermediary certificates properly indicate whether they are allowed to sign other certificates. This vulnerability highlights the importance of certificate validation in wireless security protocols and reinforces the need for comprehensive security testing of authentication mechanisms. Security teams should also consider implementing certificate pinning mechanisms and additional network monitoring to detect potential exploitation attempts. The remediation process should be prioritized at the highest security level given the remote exploitability and lack of user interaction requirements, aligning with ATT&CK technique T1566 for credential access through man-in-the-middle attacks.