Diffie-Hellman Ephemeral Key Exchange DoS Vulnerability (SSL/TLS, D(HE)ater)

[BrendanBTO]

I saw that the below 2 ciphers are ranked as secure on their respective pages. We have a vulnerability scanning tool which flagged them as being vulnerable to the below mentioned DoS vulnerability.

TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
TLS_DHE_RSA_WITH_AES_256_GCM_SHA384

https://ciphersuite.info/search/?q=TLS_DHE_RSA_WITH_AES_256_GCM_SHA

CVE-2002-20001
CVE-2022-40735

https://github.com/Balasys/dheater

https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2002-20001

https://www.researchgate.net/profile/Anton-Stiglic-2/publication/2401745_Security_Issues_in_the_Diffie-Hellman_Key_Agreement_Protocol

The Diffie-Hellman Key Agreement Protocol allows remote attackers (from the client side) to send arbitrary numbers that are actually not public keys, and trigger expensive server-side DHE modular-exponentiation calculations, aka a D(HE)ater attack. The client needs very little CPU resources and network bandwidth. The attack may be more disruptive incases where a client can require a server to select its largest supported key size. The basic attack scenario is that the client must claim that it can only communicate with DHE, and the server must be configured to allow DHE.

[n0lz]

Thanks for the info. We will look into it.