CVE-2024-23218 is a medium-severity cryptographic vulnerability affecting Apple iOS and iPadOS, as well as other Apple operating systems like macOS Sonoma, watchOS, and tvOS. The issue arises from a timing side-channel attack vector in the implementation of legacy RSA PKCS#1 v1.5 decryption. Specifically, the cryptographic functions did not fully adhere to constant-time computation principles, allowing an attacker to potentially infer information about the plaintext from the timing variations during decryption operations. This flaw enables an attacker to decrypt RSA ciphertexts without possessing the private key, effectively breaking the confidentiality of encrypted data protected by legacy RSA PKCS#1 v1.5 schemes. The vulnerability was addressed by Apple through improvements in constant-time computation in cryptographic functions, with patches released in iOS 17.3, iPadOS 17.3, macOS Sonoma 14.3, watchOS 10.3, and tvOS 17.3. The CVSS v3.1 base score is 5.9, reflecting a medium severity, with the vector indicating network attack vector (AV:N), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), high impact on confidentiality (C:H), and no impact on integrity or availability (I:N/A:N). The vulnerability is categorized under CWE-203 (Information Exposure Through Discrepancy). No known exploits in the wild have been reported to date. This vulnerability specifically affects legacy RSA PKCS#1 v1.5 ciphertexts, which are less commonly used in modern cryptographic implementations but may still be present in legacy systems or applications relying on older cryptographic standards within the Apple ecosystem.

For European organizations, the impact of CVE-2024-23218 depends largely on the extent to which legacy RSA PKCS#1 v1.5 encryption is used within their Apple device environments. Organizations that rely on Apple devices for sensitive communications or data storage and have legacy applications or systems that still use RSA PKCS#1 v1.5 encryption could face confidentiality breaches if attackers exploit this timing side-channel vulnerability. The ability to decrypt ciphertexts without the private key undermines the fundamental security guarantees of encrypted communications and data protection. This could lead to exposure of sensitive personal data, intellectual property, or confidential business information. Given the widespread use of Apple devices in European enterprises and public sector organizations, especially in sectors like finance, healthcare, and government, the vulnerability poses a moderate risk. However, the high attack complexity and the requirement for network access without privileges or user interaction somewhat limit the ease of exploitation. Nonetheless, targeted attackers with network access could leverage this vulnerability to compromise encrypted data, potentially facilitating espionage or data theft. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits following public disclosure.

European organizations should prioritize updating all Apple devices to the latest patched versions: iOS 17.3, iPadOS 17.3, macOS Sonoma 14.3, watchOS 10.3, and tvOS 17.3. This is the most effective mitigation as Apple has addressed the timing side-channel by enforcing constant-time cryptographic computations. Organizations should conduct an inventory of applications and systems that utilize legacy RSA PKCS#1 v1.5 encryption and plan to migrate to more secure cryptographic standards such as RSA-PSS or elliptic curve cryptography (ECC) where possible. Network segmentation and strict access controls should be enforced to limit exposure of vulnerable devices to untrusted networks or users. Monitoring network traffic for unusual patterns or attempts to exploit cryptographic operations may help detect exploitation attempts. Additionally, organizations should review cryptographic libraries and ensure that no custom or outdated implementations of RSA PKCS#1 v1.5 are in use. Security awareness training should include information about the importance of timely patching and the risks of legacy cryptographic algorithms. Finally, consider implementing application-layer encryption or additional layers of security for sensitive data to reduce reliance on vulnerable cryptographic primitives.