Even if you put aside the legal issues -- taking matters into your own hands can constitute a violation of the law -- hacking back could make things worse for your users. If they feel they're in a firefight, then some attackers could choose to take a more persistent approach -- targeted directly at your organization.
As security professionals, we are regularly reminded of our ethical duties to keep data safe, protect our users, and not exploit a vulnerability we did not have specific permission to attack. These things don't apply just to our daily work. Our ethical obligations extend beyond the borders of our network and even to the machines being used in attacks against us.
When's the last time you received a phishing or spear-phishing attack against your organization? Did you stop to look deeper into it, click the link, and start exploring the site that was targeting your users? There are some interesting things that can be found just by viewing the site and attempting to navigate to the root of the attack site's directory.
In some cases, I've seen attackers who were dumb enough to allow directory browsing -- which exposed the entire collection of stolen credentials to anyone who took the file name from the URL. One particular attacker left his exploit kit in the directory -- along with the address he was having the credentials emailed to. Not very smart.
But where does casual browsing of the attacking site begin to go too far?
If the attacker is storing the stolen credentials or credit card numbers alongside his phishing pages, then do not view them. You don't want the FBI knocking on your door asking what you did with the 1,500 credit card numbers you downloaded. And don't go looking for a way to delete the data, either -- you could end up destroying critical evidence that could be used to legally go after the attacker.
For targeted spear-phishing attacks, contact your local FBI office. They may help you to take the site offline and, hopefully, track down the source of the attack. You can also approach your hosting provider to get the site taken offline, which many will do immediately when they realize what's being hosted on their servers. Ideally, the hosting provider will lock the accounts and prohibit access, while preserving the data for investigation by law enforcement.
What about malware and botnets? There has been some interesting research during the past several years into botnet communications and how they can be controlled and even taken over. In 2008, European researchers learned how the Storm botnet communicates and developed an effective attack to disrupt its peer-to-peer (P2P) botnet communications.
If I know how to disrupt a botnet -- making it effectively useless -- should I do it? Not necessarily. In fact, Jose Nazario, a security researcher with Arbor Networks, told Dark Reading, "This has been a taboo subject of exploration, as people do not want to mess with other peoples' PCs by injecting commands."
He's right. Injecting commands into a botnet could have undesired effects -- from the loss of simple connectivity to serious data loss.
However, botnet research like this can be used for good, under the right circumstances. Twice in the past six months (read "Microsoft, Researchers Team Up And Tear Down Major Spamming Botnet" and "Another Botnet Gets Dismantled, But This Time With Arrests)," large botnets have been targeted and taken down as a joint effort by researchers (including those above), private companies (including Microsoft), and law enforcement. By obtaining court orders to monitor the botnet operations and its controllers, researchers were able to gain enough information to help law enforcement arrest three Mariposa botnet hunters.
Next time you consider turning the tables on the attackers, step back and remember you're becoming an attacker yourself -- and could quickly get into hot water, both with your employer and the law.
Instead, take the time to learn how tools like OSSEC HIDS and its active response capabilities can automate blocking attacker IPs without any fuss. Just remember to whitelist your critical servers first.
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