CVE-2024-23656

Dex is an identity service that uses OpenID Connect to drive authentication for other apps. Dex 2.37.0 serves HTTPS with insecure TLS 1.0 and TLS 1.1. `cmd/dex/serve.go` line 425 seemingly sets TLS 1.2 as minimum version, but the whole `tlsConfig` is ignored after `TLS cert reloader` was introduced in v2.37.0. Configured cipher suites are not respected either. This issue is fixed in Dex 2.38.0.

Dex is an identity service that uses OpenID Connect to drive authentication for other apps. Dex 2.37.0 serves HTTPS with insecure TLS 1.0 and TLS 1.1. `cmd/dex/serve.go` line 425 seemingly sets TLS 1.2 as minimum version, but the whole `tlsConfig` is ignored after `TLS cert reloader` was introduced in v2.37.0. Configured cipher suites are not respected either. This issue is fixed in Dex 2.38.0.

Dex discarding TLSconfig and always serves deprecated TLS 1.0/1.1 and insecure ciphers in github.com/dexidp/dex. NOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions. (If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.) The additional affected modules and versions are: github.com/dexidp/dex from v2.37.0 before v2.38.0.

### Summary Dex 2.37.0 is serving HTTPS with insecure TLS 1.0 and TLS 1.1. ### Details While working on https://github.com/dexidp/dex/issues/2848 and implementing configurable TLS support, I noticed my changes did not have any effect in TLS config, so I started investigating. https://github.com/dexidp/dex/blob/70d7a2c7c1bb2646b1a540e49616cbc39622fb83/cmd/dex/serve.go#L425 is seemingly setting TLS 1.2 as minimum version, but the whole tlsConfig is ignored after "TLS cert reloader" was introduced in https://github.com/dexidp/dex/pull/2964. Configured cipher suites are not respected either, as seen on the output. ### PoC Build Dex, generate certs with `gencert.sh`, modify `config.dev.yaml` to run on https, using generated certs. ```console issuer: http://127.0.0.1:5556/dex storage: type: sqlite3 config: file: dex.db web: https: 127.0.0.1:5556 tlsCert: examples/k8s/ssl/cert.pem tlsKey: examples/k8s/ssl/key.pem <rest as default> ``` Run dex `bin/dex serve config.dev.yaml`. Install `sslyze`, easy to use SSL connection analyzer: ```console pip3 install sslyze sslyze 127.0.0.1:5556 ``` In Dex 2.37.0, TLS 1.0 and TLS 1.1 are enabled in addition to expected TLS 1.2 and TLS 1.3. ```console * TLS 1.0 Cipher Suites: Attempted to connect using 80 cipher suites. The server accepted the following 6 cipher suites: TLS_RSA_WITH_AES_256_CBC_SHA 256 TLS_RSA_WITH_AES_128_CBC_SHA 128 TLS_RSA_WITH_3DES_EDE_CBC_SHA 168 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 256 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 128 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 168 ECDH: prime256v1 (256 bits) The group of cipher suites supported by the server has the following properties: Forward Secrecy OK - Supported Legacy RC4 Algorithm OK - Not Supported * TLS 1.1 Cipher Suites: Attempted to connect using 80 cipher suites. The server accepted the following 6 cipher suites: TLS_RSA_WITH_AES_256_CBC_SHA 256 TLS_RSA_WITH_AES_128_CBC_SHA 128 TLS_RSA_WITH_3DES_EDE_CBC_SHA 168 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 256 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 128 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 168 ECDH: prime256v1 (256 bits) The group of cipher suites supported by the server has the following properties: Forward Secrecy OK - Supported Legacy RC4 Algorithm OK - Not Supported * TLS 1.2 Cipher Suites: Attempted to connect using 156 cipher suites. The server accepted the following 11 cipher suites: TLS_RSA_WITH_AES_256_GCM_SHA384 256 TLS_RSA_WITH_AES_256_CBC_SHA 256 TLS_RSA_WITH_AES_128_GCM_SHA256 128 TLS_RSA_WITH_AES_128_CBC_SHA 128 TLS_RSA_WITH_3DES_EDE_CBC_SHA 168 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 256 ECDH: X25519 (253 bits) TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 256 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 128 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 128 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 168 ECDH: prime256v1 (256 bits) The group of cipher suites supported by the server has the following properties: Forward Secrecy OK - Supported Legacy RC4 Algorithm OK - Not Supported * TLS 1.3 Cipher Suites: Attempted to connect using 5 cipher suites. The server accepted the following 3 cipher suites: TLS_CHACHA20_POLY1305_SHA256 256 ECDH: X25519 (253 bits) TLS_AES_256_GCM_SHA384 256 ECDH: X25519 (253 bits) TLS_AES_128_GCM_SHA256 128 ECDH: X25519 (253 bits) ``` In Dex 2.36.0, TLS 1.0 and TLS 1.1 are disabled as expected. ```console * TLS 1.0 Cipher Suites: Attempted to connect using 80 cipher suites; the server rejected all cipher suites. * TLS 1.1 Cipher Suites: Attempted to connect using 80 cipher suites; the server rejected all cipher suites. * TLS 1.2 Cipher Suites: Attempted to connect using 156 cipher suites. The server accepted the following 5 cipher suites: TLS_RSA_WITH_AES_256_GCM_SHA384 256 TLS_RSA_WITH_AES_128_GCM_SHA256 128 TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 256 ECDH: X25519 (253 bits) TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 256 ECDH: prime256v1 (256 bits) TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 128 ECDH: prime256v1 (256 bits) The group of cipher suites supported by the server has the following properties: Forward Secrecy OK - Supported Legacy RC4 Algorithm OK - Not Supported * TLS 1.3 Cipher Suites: Attempted to connect using 5 cipher suites. The server accepted the following 3 cipher suites: TLS_CHACHA20_POLY1305_SHA256 256 ECDH: X25519 (253 bits) TLS_AES_256_GCM_SHA384 256 ECDH: X25519 (253 bits) ``` ### Impact TLS 1.0 and TLS 1.1 connections can be decrypted by the attacker, and hence decrypt the traffic to Dex.

Dex es un servicio de identidad que utiliza OpenID Connect para impulsar la autenticación de otras aplicaciones. Dex 2.37.0 sirve HTTPS con TLS 1.0 y TLS 1.1 inseguros. La línea 425 de `cmd/dex/serve.go` aparentemente establece TLS 1.2 como versión mínima, pero el `tlsConfig` completo se ignora después de que se introdujo el `TLS cert reloader` en v2.37.0. Tampoco se respetan los conjuntos de cifrado configurados. Este problema se solucionó en Dex 2.38.0.