SWEET32 Vulnerability Mitigation in Windows - CVE-2016-2183

Administration
1

The SWEET32 vulnerability exploits weaknesses in legacy block ciphers with 64-bit block size, such as 3DES, especially in CBC mode. It takes advantage of birthday attacks, focusing on the probability of a collision in the output of a function after processing large amounts of data. This vulnerability is particularly concerning for long-running encrypted sessions where the same key is repeatedly used.

Steps for Verification and Mitigation:

  1. Connection Verification:
  • Establish connections to the Windows machine through the senhasegura web proxy and RDP proxy to confirm that they are working.
  1. Security Scan:
  • Run a security scan on the Windows machine to identify active cipher suites using the command:

nmap --script ssl-enum-ciphers -p 3389 10.66.39.42
  1. Vulnerability Identification:
  • If the scan reveals the presence of the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher suite in all TLS versions, it indicates a vulnerability to the SWEET32 attack.
  1. Mitigation Steps:
  • Navigate to the registry path:

Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Cryptography\Configuration\Local\SSL\00010002
  • Remove the TLS_RSA_WITH_3DES_EDE_CBC_SHA cipher suite from the registry file named Functions.
  1. System Restart:
  • Restart the system to apply the changes made to the registry.
  1. Reevaluation:
  • Rerun the nmap command to ensure the removal of the vulnerable cipher suite.

Result:

After removing the vulnerable cipher suite, connections through the senhasegura web proxy and RDP proxy continue to function correctly, confirming the mitigation of the SWEET32 risk without impacting system operations.