CVE-2012-5820 in AdMob
Summary
by MITRE
The developer-account sample code in Google AdMob does not verify that the server hostname matches a domain name in the subject s Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.
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Analysis
by VulDB Data Team • 03/16/2019
The vulnerability described in CVE-2012-5820 represents a critical SSL/TLS certificate validation flaw within Google AdMob's developer-account sample code implementation. This weakness stems from improper certificate hostname verification during SSL connections, specifically failing to validate that the server's hostname matches either the Common Name field or Subject Alternative Name fields within the X.509 certificate structure. The flaw creates a significant security gap that directly violates fundamental SSL security principles and industry standards such as those outlined in CWE-295, which addresses "Improper Certificate Validation." This vulnerability enables man-in-the-middle attackers to successfully impersonate legitimate SSL servers by presenting arbitrary valid certificates, effectively undermining the entire SSL/TLS trust model that organizations rely upon for secure communications.
The technical implementation of this vulnerability occurs within the client-side SSL certificate validation logic of the sample code provided by Google AdMob. When establishing secure connections to AdMob services, the application fails to perform proper hostname verification against the certificate presented by the server. This validation process should typically check that the hostname used to establish the connection matches at least one of the domain names specified in the certificate's subject alternative name extension or falls within the scope of the common name field. The absence of this verification step means that an attacker with access to a valid certificate can intercept communications and present it to unsuspecting clients, making the attack transparent to end users and bypassing standard security mechanisms designed to prevent such impersonation attacks.
The operational impact of this vulnerability extends beyond simple data interception, as it fundamentally compromises the integrity of secure communications between AdMob developers and Google's servers. Attackers can exploit this weakness to conduct various malicious activities including credential theft, session hijacking, and data manipulation within the AdMob ecosystem. The vulnerability affects not only the sample code provided by Google but potentially any applications that improperly implement SSL certificate validation based on this flawed implementation. This weakness aligns with ATT&CK technique T1566.001, which describes "Phishing for Information" through credential harvesting, as attackers can leverage the compromised SSL connection to capture sensitive developer credentials and account information. The vulnerability also enables more sophisticated attacks such as data exfiltration and potential lateral movement within compromised networks where AdMob services are utilized.
Organizations and developers should implement immediate mitigations to address this vulnerability by ensuring proper SSL certificate validation is enforced in all client applications. The recommended approach involves implementing strict hostname verification that validates server certificates against the expected hostname using the standard certificate validation libraries available in most programming environments. Security measures should include verifying that the certificate's subject alternative name fields contain the expected domain name or that the common name field matches the expected hostname. Additionally, developers should consider implementing certificate pinning mechanisms where appropriate to further strengthen the security posture against this type of attack vector. The vulnerability demonstrates the critical importance of following established security best practices and adhering to standards such as RFC 2818 and RFC 6125 which specify the proper methods for hostname verification in SSL/TLS implementations. Regular security audits and code reviews should specifically examine SSL certificate validation logic to prevent similar issues from emerging in other components of the application infrastructure.