Weak TLS cipher suites remediation guide

What this finding means

SecuTest attempts a bounded set of known weak TLS 1.2 cipher suites and reports only suites accepted by the public endpoint. Legacy CBC observations are not automatically treated as proof of a specific exploit. The effective policy may differ between CDN, load balancer, and origin.

Interpretation boundary Use the exact evidence in your report. SecuTest reports externally observable conditions; it does not assume ownership, exploitability, compromise, or business intent when those cannot be proven remotely.

Associated attack or threat scenario

Threat type Cryptographic downgrade, passive decryption, and unauthenticated TLS sessions

How the attack or failure scenario works

Weak cipher suites can provide insufficient key strength, broken stream encryption, obsolete integrity algorithms, or no server authentication. A network attacker may attempt to force or intercept a connection using one of these suites. Practical exploitation depends on client support, negotiation behavior, key material, and the specific suite, but accepting them preserves avoidable attack paths.

Conditions and limitations

The public endpoint accepts at least one suite identified in the finding.
A client also offers the suite, or an attacker can influence negotiation.
Some attacks require active network positioning, large captured traffic volumes, or additional implementation weaknesses.

Why it matters

Security and business impact Accepted NULL, EXPORT, anonymous, RC4, DES, 3DES, or MD5-based suites can remove authentication or materially weaken confidentiality and integrity.

Step-by-step fix

Where to make the change

The public TLS termination point: CDN, load balancer, reverse proxy, ingress controller, or web server.
The origin server only when it directly terminates the externally observed TLS connection.

Remediation procedure

Collect the exact accepted suite names and identify the TLS termination layer that negotiated them.
Remove NULL, EXPORT, anonymous, RC4, DES, 3DES, and MD5-based suites from CDN, load balancer, reverse proxy, and directly reachable origin policies.
Prefer authenticated AEAD suites using AES-GCM or ChaCha20-Poly1305 and retain only suites required by supported clients.
Use the platform's current recommended policy instead of copying an unmaintained static cipher string.
Stage the change and monitor handshake failures before removing any documented temporary exception.

Commands and configuration examples

Replace example values with the hostname, selector, IP address, port, provider, or policy values shown in your SecuTest evidence. Review every example before production use.

openssl s_client -connect example.com:443 -servername example.com -tls1_2 -cipher 'SUITE' </dev/null

ssl_protocols TLSv1.2 TLSv1.3;
ssl_ciphers 'ECDHE+AESGCM:ECDHE+CHACHA20';
ssl_prefer_server_ciphers off;

SSLProtocol -all +TLSv1.2 +TLSv1.3
SSLCipherSuite ECDHE+AESGCM:ECDHE+CHACHA20

Verify the fix

Attempt each reported weak suite explicitly and confirm the handshake fails.
Enumerate the endpoint with an approved TLS scanner and confirm only intended modern suites remain.
Test representative browsers, API clients, mobile applications, agents, and integrations.
Run a fresh SecuTest scan against the CDN hostname and any directly reachable origin.

Confirm the externally visible result

After DNS, CDN, certificate, mail, or application propagation completes, run a fresh SecuTest scan and compare the new evidence with the original finding.

Re-scan your domain

Common mistakes

Editing cipher policy on the origin while a managed edge terminates public TLS.
Using cipher names unsupported by the deployed OpenSSL or server version.
Treating every CBC suite as proof of a named exploitable vulnerability.
Applying an overly narrow cipher list without testing required clients.

Weak TLS cipher suites