Monday, 3 July 2017

CVE-2016-2183 : Disable and stop using DES and 3DES ciphers in apache

TITLE: Birthday attacks against TLS ciphers with 64bit block size vulnerability (Sweet32)
CVEID: CVE-2016-2183

We need to add DES and 3DES in /etc/httpd/conf.modules.d/ssl.conf file in order to disable it.

Look for SSLCipherSuite line

[root@test ~]# grep SSLCipherSuite /etc/httpd/conf.modules.d/ssl.conf
  SSLCipherSuite HIGH:MEDIUM:!aNULL:!MD5:!RC4
[root@test ~]#

Modify like below

[root@test ~]# grep SSLCipherSuite /etc/httpd/conf.modules.d/ssl.conf
  SSLCipherSuite HIGH:MEDIUM:!aNULL:!MD5:!RC4:!DES:!3DES
[root@test ~]#

Restart the required services for the port which u got vulnerability.

The following openssl commands can be used to do a manual test:
openssl s_client -connect ip:port -cipher "DES:3DES" -ssl2
openssl s_client -connect ip:port -cipher "DES:3DES" -ssl3
openssl s_client -connect ip:port -cipher "DES:3DES" -tls1
openssl s_client -connect ip:port -cipher "DES:3DES" -tls1_1
openssl s_client -connect ip:port -cipher "DES:3DES" -tls1_2


[root@test ~]# openssl s_client -connect 10.10.10.1:443 -cipher "DES:3DES" -tls1_2
CONNECTED(00000003)
140592171460512:error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake failure:s3_pkt.c:1275:SSL alert number 40
140592171460512:error:1409E0E5:SSL routines:SSL3_WRITE_BYTES:ssl handshake failure:s3_pkt.c:598:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 7 bytes and written 0 bytes
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1.2
    Cipher    : 0000
    Session-ID:
    Session-ID-ctx:
    Master-Key:
    Key-Arg   : None
    Krb5 Principal: None
    PSK identity: None
    PSK identity hint: None
    Start Time: 1499085145
    Timeout   : 7200 (sec)
    Verify return code: 0 (ok)
---
[root@test ~]#


No comments:

Post a Comment