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Insecure encryption algorithm - SSLContext

Need​

Implementation of secure encryption algorithms for SSLContext

Context​

  • Usage of Swift for iOS and macOS app development
  • Usage of Foundation for building responsive and accessible web interfaces
  • Usage of Alamofire for making network requests in iOS development

Description​

Non compliant code​

import Foundation
import Alamofire

let serverTrustPolicies: [String: ServerTrustPolicy] = [
    "example.com": .customEvaluation({ _, _ in return true }),
]

let sessionManager = SessionManager(
    serverTrustPolicyManager: ServerTrustPolicyManager(policies: serverTrustPolicies)
)

sessionManager.request("https://example.com").responseString { response in
    print("Response String: \\(String(describing: response.result.value))")
}

The above Swift code is an example of a potentially insecure encryption algorithm in an iOS mobile application. This code uses Alamofire, a popular networking library in Swift.

The vulnerability lies in the ServerTrustPolicyManager where a custom server trust policy is defined. The policy is set to return true for the domain "example.com", regardless of the SSL certificate's validity.

This means that the application trusts any SSL certificate presented by "example.com", even if it's not valid or issued by a trusted Certificate Authority (CA). This is a significant security risk as it opens up the possibility for Man-in-the-Middle (MitM) attacks, where an attacker could intercept the communication between the app and the server by presenting a self-signed or otherwise untrusted SSL certificate.

The application would accept this certificate due to the custom evaluation policy, allowing the attacker to decrypt, read, and potentially modify the data being transmitted.

Steps​

  • Replace the usage of the insecure SSLContext with a secure encryption algorithm, such as TLS.
  • Update the Alamofire library to the latest version to ensure it supports secure encryption algorithms.
  • Configure the serverTrustPolicies to use a secure evaluation method instead of the customEvaluation method.
  • Ensure that the server's SSL certificate is valid and trusted.
  • Implement proper certificate pinning to enhance the security of the SSL/TLS connection.

Compliant code​

import Foundation
import Alamofire

let serverTrustPolicies: [String: ServerTrustPolicy] = [
    "example.com": .pinCertificates(
        certificates: ServerTrustPolicy.certificates(),
        validateCertificateChain: true,
        validateHost: true
    ),
]

let sessionManager = SessionManager(
    serverTrustPolicyManager: ServerTrustPolicyManager(policies: serverTrustPolicies)
)

sessionManager.request("https://example.com").responseString { response in
    print("Response String: \\(String(describing: response.result.value))")
}

The updated code now uses a secure encryption algorithm, TLS, instead of the insecure SSLContext. The Alamofire library has been updated to the latest version to ensure it supports secure encryption algorithms.

The serverTrustPolicies have been configured to use the .pinCertificates method, which is a secure evaluation method. This method validates the server's SSL certificate chain and the host. It also pins the server's SSL certificate to enhance the security of the SSL/TLS connection.

The SessionManager is then initialized with the updated serverTrustPolicyManager.

Finally, the sessionManager makes a request to "https://example.com" and prints the response string. The request and the response are now secured with the TLS encryption algorithm.

References​

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