In July 2024, a data broker called National Public Data confirmed a breach that exposed the personal information of hundreds of millions of people — names, addresses, phone numbers, and Social Security numbers sold on a dark web forum before the company even acknowledged the incident publicly. The breach ultimately drove National Public Data into bankruptcy. The stolen data is still circulating.
In 2024, over 703 million personal data records were discovered on dark web marketplaces — a 28% increase from 2023. Nearly 34% of all data breach incidents that year involved content eventually shared or sold on the dark web. More than 140 million stolen credit card records appeared for sale on dark web listings in 2025. And in July 2024, a leak called RockYou2024 exposed approximately 10 billion unique plaintext passwords — the largest credential dump in recorded history.
Most people have a vague awareness that the dark web exists and that stolen data ends up there. Far fewer understand how this actually works, what their data is worth, what criminals do with it, and — most importantly — what they can do to limit the damage before and after a breach. This article answers all of those questions.
What the Dark Web Actually Is
The internet most people use daily — websites indexed by Google, accessible through normal browsers — represents only a fraction of total internet content. The deep web refers to all content not indexed by search engines: private databases, email inboxes, banking portals, subscription content, and countless other resources that require authentication to access. This portion is enormous and entirely legitimate.
The dark web is a much smaller subset of the deep web, accessible only through specialized software like the Tor browser, which routes traffic through multiple encrypted relays to anonymize users. Tor was originally developed by the US Naval Research Laboratory for secure military communications and remains widely used for legitimate privacy purposes — by journalists, activists, people in authoritarian countries, and ordinary users concerned about surveillance.
The same anonymity properties that make Tor valuable for legitimate privacy also make it attractive for criminal operations. Approximately 60% of dark web content involves illegal activity: stolen data marketplaces, drug trafficking, cybercrime-as-a-service offerings, and fraud tools. Dark web sales reached an estimated $2.6 billion in 2025, according to blockchain analysis firm Chainalysis.
How Your Data Gets There
Data arrives on dark web marketplaces through several distinct pathways, each representing a different type of security failure:
Corporate data breaches are the primary source. When companies that hold your information — retailers, healthcare providers, financial institutions, data brokers — are attacked, the stolen records are almost always sold or posted on dark web forums. The timeline varies: some breaches are monetized within hours; others are stockpiled and sold months or years later when the initial urgency of detection fades. According to Bitsight research, 45% of breaches in 2024 were shared freely on underground forums rather than sold — meaning your data may be widely available even when no direct financial transaction occurred.
Infostealer malware silently harvests credentials from infected devices. This category of malware, which infected over 1 billion devices in 2024 according to security researchers, captures usernames and passwords as you type them, extracts stored browser passwords, and exfiltrates session cookies that allow attackers to access accounts without needing your password at all. The harvested credentials are compiled into logs and sold in bulk on dark web markets.
Phishing campaigns extract credentials directly from victims. When someone enters their username and password into a convincing fake website, those credentials are captured and typically sold or used within hours. Professional phishing operations sell credentials sorted by account type — banking credentials command the highest prices, followed by cryptocurrency exchange accounts.
Data scraping collects publicly available information at scale. Automated tools harvest personal details from social media profiles, public records databases, and business directories. While individual pieces may be publicly visible, aggregated profiles combining dozens of data points from multiple sources are far more valuable and dangerous than any single element.
What Your Data Is Worth and How It Gets Used
The dark web economy prices personal data based on its utility for fraud. Understanding these price points helps clarify what attackers are actually trying to accomplish with your information:
Credit card data with full details (card number, expiration, CVV, billing address) sold for between $5 and $20 per record in 2024-2025 markets, with higher prices for cards with higher limits and verified billing addresses. In 2025, over 140 million such records were available. Cards are typically used quickly for fraudulent purchases before the owner or bank detects unauthorized activity.
Banking login credentials command significantly higher prices — between $40 and several hundred dollars depending on the account balance — because they enable direct fund transfers rather than just single purchases. Accounts with balances over $10,000 can sell for 10% of the balance or more.
Full identity packages, sometimes called “fullz,” bundle a person’s name, Social Security number, date of birth, address, and financial account details. These sell for between $15 and $65 and enable the most damaging forms of identity theft: opening new credit accounts, filing fraudulent tax returns, and taking out loans.
Email account access is valuable not for the account itself but for what it enables — password reset access to every other account linked to that email. Email credentials sell for as little as $1 to $3 for personal accounts but far more for corporate accounts.
Once purchased, stolen data is used for credential stuffing attacks (automatically testing credentials across hundreds of websites), account takeover fraud, new account fraud (opening credit lines in victims’ names), tax identity theft, and resale to other criminals in the chain.
How to Find Out If Your Data Is Already Out There
Several free tools allow anyone to check whether their email address or passwords have appeared in known data breaches:
HaveIBeenPwned.com, maintained by security researcher Troy Hunt and used by government agencies around the world, allows you to enter your email address and receive a complete list of every known breach in which that address appeared. It also allows you to check specific passwords against its database of known breached passwords — without sending the actual password to the site (the check uses a cryptographic technique called k-anonymity). Check this site for every email address you use regularly. If breaches appear, change the passwords for those accounts immediately, especially if you reused that password elsewhere.
Google’s Password Checkup, accessible through your Google account at passwords.google.com, automatically checks your saved passwords against known breached credential databases and alerts you to compromised, reused, or weak passwords.
Firefox Monitor at monitor.firefox.com provides similar breach monitoring and can send you alerts when your email address appears in new breaches.
For more comprehensive monitoring, many credit card issuers and banks now include dark web monitoring as a free feature of their accounts — checking whether your financial account information appears on dark web marketplaces. Check whether your existing financial institutions offer this service before paying for a third-party monitoring service.
Reducing Your Exposure Before a Breach Happens
While you cannot prevent companies from being breached, you can significantly limit how useful your data is to attackers when it inevitably leaks:
Use unique passwords for every account. This is the single most impactful step. When a company is breached and credentials leak, attackers immediately attempt those credentials on every major service. A unique password for every account means a breach at one service exposes only that account, not everything else you own. A password manager makes this effortless.
Use an email alias service for account registrations. Services like Apple’s Hide My Email, SimpleLogin, or DuckDuckGo Email Protection generate unique email addresses for each service you sign up for. When a company you registered with is breached, only that alias is exposed — not your real email address. You can disable the alias immediately after a breach without affecting any other account.
Minimize what you share when registering for services. Many sites ask for more information than they need. A date of birth is required for age verification but rarely needs to be your actual birth date. A phone number may be optional for many services. The less accurate information a company holds about you, the less useful that information is to an attacker who later acquires it.
Enable two-factor authentication on your most important accounts. Even if your password is exposed in a breach and an attacker tries to use it, 2FA means that credential alone is not sufficient to access your account. Email and financial accounts especially should have 2FA enabled.
Freeze your credit at all three bureaus. A credit freeze prevents new credit from being opened in your name even if an attacker has your Social Security number and full personal details. This is free, does not affect your credit score, and can be temporarily lifted when you need to apply for credit. For most people not actively applying for credit, a permanent freeze is the most effective protection against new account fraud.
What to Do When Your Data Has Already Been Exposed
If you discover your information has appeared in a breach, the appropriate response depends on what type of data was exposed:
If email and password were exposed: change the password immediately on that service and anywhere else you used the same password. Enable 2FA on the affected account. Monitor the email address for unusual activity.
If financial account information was exposed: contact your bank or card issuer immediately. Most will issue new account numbers proactively when there is evidence of exposure. Place a fraud alert or credit freeze at all three bureaus. Monitor your accounts and credit reports closely for the following 12 months.
If your Social Security number was exposed: place a credit freeze at all three bureaus immediately. Consider placing an Identity Protection PIN with the IRS to prevent fraudulent tax filings using your SSN — this is a free service at IRS.gov/ippin. Monitor your Social Security earnings record at ssa.gov annually for signs of employment identity theft.
Frequently Asked Questions
Q: Should I try to access the dark web to check if my data is there?
A: No. The free monitoring tools described above — HaveIBeenPwned, Google Password Checkup, your bank’s dark web monitoring — provide the information you need without the significant risks associated with accessing dark web marketplaces directly. Most people who attempt to access dark web fraud markets without expertise expose themselves to malware, scams within those markets, and potential legal complications. The legitimate monitoring tools are sufficient and far safer.
Q: My information was in the National Public Data breach. What should I do?
A: The National Public Data breach exposed names, addresses, phone numbers, and Social Security numbers for hundreds of millions of people. If you are potentially affected — and given the scale, most US adults should assume they are — place a credit freeze at all three bureaus, set up an IRS Identity Protection PIN, and check HaveIBeenPwned for your email addresses. Monitor your credit reports regularly for unfamiliar accounts or inquiries.
Q: Can data be removed from the dark web after it has been posted?
A: Once data has been posted or sold on dark web forums, it effectively cannot be removed. Copies are made immediately and distributed across multiple parties. The focus after a breach must be on making the data less useful to attackers — by changing compromised passwords, enabling 2FA, and freezing credit — rather than attempting removal, which is not practically achievable.
Q: How long after a breach can stolen data still be used against me?
A: This is one of the most important and underappreciated aspects of data breach risk. Stolen data is frequently held for months or years before being used. Attackers stockpile breach data and use it opportunistically. A breach from 2019 may generate fraud attempts in 2025 when the data is combined with information from more recent breaches. This is why ongoing monitoring — not just a one-time check after a known breach — is the appropriate long-term response.
