TLS 1.0 vulnerability over 993 IMAPS

[mehdi]

@d19dotca This tests the TLS of the HTTPS server. @Mastadamus is talking about the TLS of the IMAPS server.

[d19dotca]

@mehdi Ah yeah funny enough I just realized that haha I'm checking mine out as we speak for the mail server.

[d19dotca]

I'm still not seeing anything about TLSv1.0 enabled on the mail domain either. @Mastadamus - are you able to explain how to reproduce this test so people can check out their own instances? So far I'm not able to reproduce.

[Mastadamus]

@d19dotca I used the qualys vulnerability scanner community edition. You need to create an qualys account and use the actual vulnerability scanner. Also if you are running a firewall, you may have to unblock the qualys IP if it auto blocks it when it attempts various "scans' like checking for heartbleed etc. you can sign up for here https://www.qualys.com/community-edition/

[girish]

@mastadamus thanks for reporting! Initially, I thought this was a false alarm because tls1 connections don't work:

openssl s_client -connect my.example.com:993 -tls1
CONNECTED(00000003)
140461753824576:error:141E70BF:SSL routines:tls_construct_client_hello:no protocols available:../ssl/statem/statem_clnt.c:1112:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 7 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---

Investigating further, I found that s_client can also fail if there is cipher match. And doing a "scan":

$ nmap --script ssl-enum-ciphers my.example.com -p 993
Starting Nmap 7.80 ( https://nmap.org ) at 2021-02-20 09:50 PST
Nmap scan report for my.example.com (45.55.2.141)
Host is up (0.013s latency).

PORT    STATE SERVICE
993/tcp open  imaps
| ssl-enum-ciphers: 
|   TLSv1.0: 
|     ciphers: 
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 1024) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp384r1) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_SEED_CBC_SHA (rsa 4096) - A
|     compressors: 
|       NULL
|     cipher preference: client
|     warnings: 
|       Key exchange (dh 1024) of lower strength than certificate key
|   TLSv1.1: 
|     ciphers: 
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 1024) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp384r1) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_SEED_CBC_SHA (rsa 4096) - A
|     compressors: 
|       NULL
|     cipher preference: client
|     warnings: 
|       Key exchange (dh 1024) of lower strength than certificate key
|   TLSv1.2: 
|     ciphers: 
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_128_CCM (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_128_CCM_8 (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_CCM (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_CCM_8 (dh 1024) - A
|       TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (dh 1024) - A
|       TLS_DHE_RSA_WITH_ARIA_128_GCM_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_ARIA_256_GCM_SHA384 (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA (dh 1024) - A
|       TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (dh 1024) - A
|       TLS_DHE_RSA_WITH_SEED_CBC_SHA (dh 1024) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_ARIA_128_GCM_SHA256 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_ARIA_256_GCM_SHA384 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_CAMELLIA_128_CBC_SHA256 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_CAMELLIA_256_CBC_SHA384 (secp384r1) - A
|       TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256 (secp384r1) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_AES_128_CBC_SHA256 (rsa 4096) - A
|       TLS_RSA_WITH_AES_128_CCM (rsa 4096) - A
|       TLS_RSA_WITH_AES_128_CCM_8 (rsa 4096) - A
|       TLS_RSA_WITH_AES_128_GCM_SHA256 (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_CBC_SHA256 (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_CCM (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_CCM_8 (rsa 4096) - A
|       TLS_RSA_WITH_AES_256_GCM_SHA384 (rsa 4096) - A
|       TLS_RSA_WITH_ARIA_128_GCM_SHA256 (rsa 4096) - A
|       TLS_RSA_WITH_ARIA_256_GCM_SHA384 (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_128_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_128_CBC_SHA256 (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_256_CBC_SHA (rsa 4096) - A
|       TLS_RSA_WITH_CAMELLIA_256_CBC_SHA256 (rsa 4096) - A
|       TLS_RSA_WITH_SEED_CBC_SHA (rsa 4096) - A
|     compressors: 
|       NULL
|     cipher preference: client
|     warnings: 
|       Key exchange (dh 1024) of lower strength than certificate key
|_  least strength: A

Nmap done: 1 IP address (1 host up) scanned in 5.43 seconds

So, looks like something we have to disable in dovecot. We had disabled this in Haraka (the SMTP server) but not dovecot it seems. You can run nmap on port 587 to verify.

[girish]

Ah nice, it seems the upgrade of the base image to bionic already fixed this since it comes with a newer dovecot.

$ nmap --script ssl-enum-ciphers my.example.com -p 993
Starting Nmap 7.80 ( https://nmap.org ) at 2021-02-20 09:59 PST
Nmap scan report for my.example.com (142.93.86.76)
Host is up (0.014s latency).


PORT    STATE SERVICE
993/tcp open  imaps
| ssl-enum-ciphers: 
|   TLSv1.2: 
|     ciphers: 
|       TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_128_CCM (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_256_CCM (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_256_CCM_8 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_ARIA_128_GCM_SHA256 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_ARIA_256_GCM_SHA384 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_CAMELLIA_128_CBC_SHA256 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_CAMELLIA_256_CBC_SHA384 (secp256r1) - A
|       TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256 (secp256r1) - A
|     compressors: 
|       NULL
|     cipher preference: client
|     warnings: 
|       Key exchange (secp256r1) of lower strength than certificate key
|_  least strength: A

[Mastadamus]

Hey, glad I could be of service. Thanks for the quick replies and thankfully, its quickly remedied.

[Mastadamus]

@girish sir

BTW, I apologize for not using your dedicated vulnerability reporting method.

1. I just read up on it
2. I really thought it was due to a settings misconfiguration part on my end and a false alarm as well. I was initially just looking for Guidance on fixing what I set up wrong. In the future if it's vulnerability concerned, I'll use your reporting mechanisms.

[girish]

@mastadamus no problem! atleast, this is not a severe security issue and we have a fix coming already.

[Mastadamus]

@girish agreed.