1. Vulnerability Description
- DROWN attack decrypts HTTPS connection by sending malicious packet specially designed by attacker to server, or MITM attack can be executed if certificate is shared with other server
2. How to check vulnerability
- Check the usage component version.
Apache
- Any version other than 2.4.x
Nginx
- 0.7.64, 0.8.18, and earlier versions
Postfix
- 2.9.14, 2.10.8, 2.11.6, 3.0.2, and earlier versions
OpenSSL
- 1.0.2a, 1.0.1m, 1.0.0r, 0.9.8zf, and earlier versions
3. Vulnerability Countermeasure
OpenSSL
- Upgrade OpenSSL to latest version
- How to upgrade
- In case of CentOS, Redhat
# yum clean
# yum update openssl
- In case of Ubuntu
# apt-get upgrade openssl
IIS / NSS
Apache
- Disable SSLv2.
- Change the Apache configuration file (httpd.conf)
# vi httpd.conf
......
SSLProtocol -all +TLSv1.2
SSLCipherSuite HIGH:!aNULL:!MD5:!SSLv2:!SSLv3:!TLSv1
......
# service httpd restart
Nginx
ssl_protocols TLSv1.2;
4. Reference
SSL/TLS usage recommendations (as of December 2019)
