OpenSSL DROWN溺亡漏洞的检测及修复方法分析

 一、漏洞描述： 现在流行的服务器和客户端使用TLS加密,SSL和TLS协议保证用户上网冲浪,购物,即时通信而不被第三方读取到。DROWN(溺亡)漏洞允许攻击者破坏这个加密体系,通过“中间人劫持攻击”读取或偷取敏感通信,包括密码,信用卡帐号,商业机密,金融数据等。

二、漏洞影响： 
大部分支持SSLv2的服务器均会受到该漏洞影响，比如启用了ssl、tls加密的web服务器、邮件服务器。

三、检测方法： 
你也可使用检测工具检查，下载地址： 
https://github.com/nimia/public_drown_scanner

四、修复方法： 
确保你的私钥不适用于其他的支持sslv2服务,包括web,smtp,imap,pop服务等。禁止服务器端的sslv2支持。如果是Openssl,请查看OpenSSL官方给出的修复指南。 
https://www.openssl.org/blog/blog/2016/03/01/an-openssl-users-guide-to-drown/

如果是nginx服务器直接在nginx.conf配置文件中去掉ssl_protocols SSLv2的支持。

示例： 
[root@yn_vm_dev46 public_drown_scanner]# yum install python-virtualenv

[root@yn_vm_dev46 public_drown_scanner]# virtualenv drown 
New python executable in drown/bin/python 
Installing Setuptools………………………………………………………………………………………done. 
Installing Pip……………………………………………………………………………………………………….done.
[root@yn_vm_dev46 public_drown_scanner]# 
[root@yn_vm_dev46 public_drown_scanner]# 
[root@yn_vm_dev46 public_drown_scanner]# cd drown/ 
[root@yn_vm_dev46 drown]# ls 
bin include lib lib64 
[root@yn_vm_dev46 drown]# ./bin/activate 
-bash: ./bin/activate: Permission denied 
[root@yn_vm_dev46 drown]# . ./bin/activate 
(drown)[root@yn_vm_dev46 drown]# 
(drown)[root@yn_vm_dev46 drown]# 
(drown)[root@yn_vm_dev46 drown]# pip install enum pycrypto scapy pyasn1 scapy-ssl_tls

(drown)[root@yn_vm_dev46 drown]# python /root/public_drown_scanner/scanner.py www.com 443 
Testing www.com on port 443 
www.com: Server is vulnerable, with cipher RC2_128_CBC_EXPORT40_WITH_MD5

www.com: Server is vulnerable, with cipher RC4_128_EXPORT40_WITH_MD5

www.com: Case 7; Symmetric key did not successfully verify on server finished message 
www.com: Server is NOT vulnerable with cipher RC4_128_WITH_MD5, Message: 7: no tls

www.com: Server is vulnerable, with cipher DES_64_CBC_WITH_MD5

(drown)[root@yn_vm_dev46 drown]# python /root/public_drown_scanner/scanner.py www.com 443 
Testing www.com on port 443 
www.com: Case 3b; Connection reset by peer when waiting for server hello 
www.com: Server is NOT vulnerable with cipher RC2_128_CBC_EXPORT40_WITH_MD5, Message: 3b: no tls

www.com: Case 3b; Connection reset by peer when waiting for server hello 
www.com: Server is NOT vulnerable with cipher RC4_128_EXPORT40_WITH_MD5, Message: 3b: no tls

www.com: Case 3b; Connection reset by peer when waiting for server hello 
www.com: Server is NOT vulnerable with cipher RC4_128_WITH_MD5, Message: 3b: no tls

www.com: Case 3b; Connection reset by peer when waiting for server hello 
www.com: Server is NOT vulnerable with cipher DES_64_CBC_WITH_MD5, Message: 3b: no tls