Gallery: The top zero day Dark Web markets

How zero day exploits are bought and sold

Kapustkiy won't buy malware, but the hacker claims to sell zero day exploits, software loopholes that allow attackers to exploit software and networks. "I can't name the site I use, but I think that most hackers would use the same [sites]," he said. Kapustkiy is a young, ideologically driven hacker who frequently tunnels into government and corporate sites. "I hack for political reasons," he said in translated, broken English, "but make money sometimes from selling hacks."

Zero day exploits are a major profit center for many hackers and are at the heart of underground cyberwar ecosystem. Though bug bounty programs are a common white hat practice for major websites and software vendors, under the clearnet is a thriving Dark Web market for malicious code. Malware and software bugs can sell for tens or hundreds of thousands of dollars on the Dark Web.

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Zero day bugs are valuable because of the high stakes for victims. Bugs in Flash or Windows grant hackers easy access to corporate systems. Malware in the form of Stuxnet was allegedly developed and deployed by the United States and Israel to attack Iran's nuclear program, and Sandworm was allegedly used by Russian hackers to attack NATO.

To hack a major foreign embassy Kapustkiy claimed, for example, he "started by scanning the websites from the [embassy] websites to see which were related to the [primary site]. I got a huge list of around 20 domains and I saw that all of them were running on the same server and also had the same vulnerability. So I found a exploit in the web-server and I managed to hack [several sites]. It was very simple because all of the websites were running on the same server."

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Enterprise companies and SMBs are vulnerable to a similar attack, he said, and sensitive corporate data is frequently swiped then sold on the Dark Web. "I just found a SQL [hole] in the website," Kapustkiy said, "nothing special. They fixed [the hole] but I could still manage to hack the website with social engineering. The administrator was still using the same password and I could get access to a lot of his personal information."

The hackers and groups in the market for zero day exploits are as diverse as the code they're selling. Each actor has different methods of exploitation and uses a variety of sites to offload code in exchange for Bitcoin. Though Dark Web malware markets tend to appear then vanish, these are ten of the most well-known and widely used hacker websites and forms.

Before you hop on Tor and begin poking around, novices and experts alike should remember to exercise care and caution when visiting the Dark Web. Though many of these sites return benign content, much of the Dark Web is NSFW. TechRepublic does not condone illegal or unethical activity. Offensive material can sometimes be just a click away. Browse at your own risk. Never break the law. Use the Dark Web safely, and for legal purposes only.

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By Dan Patterson

Dan is a writer, reporter, and producer. He is currently a reporter for at CBS News and was previously a Senior Writer for TechRepublic.