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Insecure encryption algorithm - Anonymous cipher suites


The application allows connections with anonymous cipher suites.


Obtain sensitive information by performing a MitM attack.


Use algorithms considered cryptographically secure.


Unauthorized attacker from adjacent network performing a MitM attack.

Expected Remediation Time

⌚ 30 minutes.


Default score using CVSS 3.1. It may change depending on the context of the vulnerability.


  • Attack vector: N
  • Attack complexity: L
  • Privileges required: N
  • User interaction: N
  • Scope: U
  • Confidentiality: N
  • Integrity: N
  • Availability: N


  • Exploit code madurity: X
  • Remediation level: X
  • Report confidence: X


  • Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N/E:X/RL:X/RC:X
  • Score:
    • Base: 0.0
    • Temporal: 0.0
  • Severity:
    • Base: None
    • Temporal: None

Code Examples

Compliant code

The application has secure cipher algorithms set

http {
server {
index: "index.html";
listen: "localhost:4446 ssl";
server_name: "localhost";
ssl_prefer_server_ciphers: "on";
ssl_ciphers: "TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384";
ssl_certificate: "cert.crt";
ssl_certificate_key: "cert.key";
ssl_protocols: "SSLv3 TLSv1.2";

Non compliant code

There are insecure cipher algorithms used in the application

http {
server {
index: "index.html";
listen: "localhost:4446 ssl";
server_name: "localhost";
ssl_prefer_server_ciphers: "off";
ssl_ciphers: "TLS_DH_RSA_WITH_SEED_CBC_SHA";
ssl_certificate: "cert.crt";
ssl_certificate_key: "cert.key";
ssl_protocols: "SSLv3 TLSv1 TLSv1.1";


A cipher suite is a set of algorithms that help secure a network connection. Suites typically use Transport Layer Security (TLS) or its now-deprecated predecessor Secure Socket Layer (SSL). The set of algorithms that cipher suites usually contain include: a key exchange algorithm, a bulk encryption algorithm, and a message authentication code (MAC) algorithm.

The key exchange algorithm is used to exchange a key between two devices. This key is used to encrypt and decrypt the messages being sent between two machines.

The bulk encryption algorithm is used to encrypt the data being sent.

The MAC algorithm provides data integrity checks to ensure that the data sent does not change in transit. In addition, cipher suites can include signatures and an authentication algorithm to help authenticate the server or client.

A cipher suite is as secure as the algorithms that it contains. If the version of encryption or authentication algorithm in a cipher suite have known vulnerabilities, the cipher suite and TLS connection is then vulnerable.

Weak algorithms

  • RSA with key < 2048 bytes, can be brute-forced in feasible time

  • OpenSSL Elliptic Curves, secp112r1, secp112r2, secp128r1, secp128r2, secp160k1, secp160r1, secp160r2, secp192k1, prime192v1, prime192v2, prime192v3, sect113r1, sect113r2, sect131r1, sect131r2, sect163k1, sect163r1, sect163r2, sect193r1, sect193r2, c2pnb163v1, c2pnb163v2, c2pnb163v3, c2pnb176v1, c2tnb191v1, c2tnb191v2, c2tnb191v3, c2pnb208w1, wap-wsg-idm-ecid-wtls1, wap-wsg-idm-ecid-wtls3, wap-wsg-idm-ecid-wtls4, wap-wsg-idm-ecid-wtls5, wap-wsg-idm-ecid-wtls6, wap-wsg-idm-ecid-wtls7, wap-wsg-idm-ecid-wtls8, wap-wsg-idm-ecid-wtls9, wap-wsg-idm-ecid-wtls10, wap-wsg-idm-ecid-wtls11, oakley-ec2n-3, oakley-ec2n-4, brainpoolp160r1, brainpoolp160t1, brainpoolp192r1, brainpoolp192t1, can be brute-forced in feasible time.