Leaked Credentials
Credentials Dark Web Data Breaches InfoStealers
What Are Leaked Credentials? Leaked credentials are usernames, passwords, session tokens, API keys, and other …
Compromised credentials are the starting point for most cyberattacks. They give attackers a legitimate way into your systems.
According to IBM’s 2025 Cost of a Data Breach Report, breaches involving stolen credentials cost $4.67 million on average. They also take 246 days to identify and contain.
Here’s what you need to know about compromised credentials, how they differ from leaked credentials, and how to detect credential compromise before attackers can exploit it.
Contents
What Are Compromised Credentials?
Compromised credentials are usernames, passwords, session tokens, API keys, or other authentication data that have been stolen and are actively being exploited or at immediate risk of exploitation. Credentials become compromised through infostealer malware, phishing attacks, or when attackers purchase them from criminal marketplaces to use in targeted attacks.
The term “compromised” implies active risk. These aren’t old passwords sitting in decade-old breach dumps. Compromised credentials are fresh, working, and in the hands of attackers who intend to use them. According to the Verizon Data Breach Investigations Report, over 80% of hacking-related breaches involve stolen or weak credentials.
Compromised credentials can include:
- Usernames and passwords: The most common type, used for direct account access
- Session tokens and cookies: Allow attackers to hijack authenticated sessions without knowing the password
- API keys and access tokens: Provide programmatic access to cloud services and applications
- MFA backup codes: Enable authentication bypass if the primary MFA method fails
- OAuth tokens: Grant persistent access to connected applications
What’s the Difference Between Leaked and Compromised Credentials?
Understanding this distinction matters for security teams. The response to leaked credentials differs from the response to compromised credentials.
| Aspect | Leaked Credentials | Compromised Credentials |
|---|---|---|
| Status | Exposed to unauthorized parties | Actively exploited or at immediate risk |
| Timeframe | May sit dormant for months or years | Being used or about to be used |
| Detection | Found in breach dumps, dark web | Detected through behavioral anomalies or threat intelligence |
| Response | Proactive password reset | Immediate lockdown required |
| Risk Level | Potential threat | Active threat |
Leaked credentials are exposed but may never be used. They appear in data breaches, combo lists, and public dumps. A password leaked in 2019 might still work today, but if no one has tested it, the account remains safe.
Compromised credentials are actively dangerous. They’re in the hands of attackers who plan to use them. This includes credentials captured by infostealers and uploaded to criminal infrastructure within minutes, credentials purchased from dark web marketplaces by attackers planning specific attacks, and credentials being tested in real-time credential stuffing campaigns.
The goal of credential monitoring is to detect leaked credentials before they become compromised. When you find your credentials in an infostealer log or dark web listing, you can reset them before attackers exploit them.
How Do Credentials Become Compromised?
Credentials move from “safe” to “compromised” through several attack vectors. Understanding these paths helps you defend against them.
Infostealer malware infections are the primary source of compromised credentials today. When someone downloads malicious software, the infostealer harvests every saved password in their browser, active session cookies, and autofill data. This data uploads to attacker servers within minutes. What makes infostealers particularly dangerous is the freshness and completeness of stolen data. These aren’t hashed passwords from old breaches. They’re plaintext credentials with active session tokens that bypass MFA entirely. According to M-Trends 2025, stolen credentials now account for 16% of initial infection vectors, up from 10% in 2023.
Phishing and social engineering trick users into entering credentials on fake login pages. Modern phishing kits capture not just passwords but MFA codes in real-time, forwarding them to attackers before they expire. Social engineering goes further, manipulating people into revealing credentials directly. Attackers impersonate IT support, executives, or trusted vendors.
Third-party data breaches expose your credentials when companies you use get hacked. You might have perfect password hygiene, but if a service you use gets breached, your credentials are exposed. The danger multiplies with password reuse. A Cybernews study of 19 billion leaked passwords found 94% are reused or duplicated.
Credential stuffing takes previously leaked credentials and tests them against new targets at scale. Attackers use botnets to distribute credential stuffing attacks across thousands of IP addresses. When credential stuffing succeeds, leaked credentials become compromised credentials.
Session hijacking doesn’t require passwords at all. Stolen session tokens let attackers hijack authenticated sessions directly. They import the stolen cookie and continue where the legitimate user left off, bypassing MFA entirely.
What Are the Warning Signs of Compromised Credentials?
Detecting credential compromise early limits the damage. Watch for these indicators.
Impossible travel alerts. Logins from geographically distant locations within a short timeframe indicate credential compromise. Legitimate users don’t teleport from New York to Singapore in an hour.
Multiple failed login attempts. A spike in failed authentications followed by a successful login often indicates credential stuffing or password guessing. The failures represent testing; the success represents a match.
Unexpected MFA prompts. When users receive MFA requests they didn’t initiate, attackers may be testing stolen credentials. MFA fatigue attacks bombard users with approval requests hoping they’ll eventually click yes.
Account setting changes. Attackers often modify account settings after gaining access. They add their own email address for password resets, change phone numbers for SMS verification, or disable notifications to hide their activity.
Unusual access patterns. Watch for users accessing systems or data they don’t normally touch. A finance employee suddenly downloading engineering documents should trigger an investigation.
What Happens When Credentials Are Compromised?
Compromised credentials enable a range of attacks. The damage depends on what accounts are compromised and how quickly you detect and respond.
Account takeover. Attackers log in, change passwords, and lock out legitimate users. They access personal information, financial data, and anything else stored in the account. Learn more about account takeover attacks.
Lateral movement. One compromised account leads to others. Attackers use their initial foothold to harvest more credentials, access shared resources, and expand control throughout the network.
Data exfiltration. Compromised accounts provide access to sensitive data. Customer information, intellectual property, and confidential communications can all be stolen.
Ransomware deployment. Many ransomware attacks begin with compromised VPN or RDP credentials. Attackers buy valid credentials, gain initial access, move laterally, then deploy ransomware across the network.
Financial fraud. Compromised banking credentials lead to unauthorized transfers. Business email compromise uses compromised email accounts to authorize fraudulent payments.
How Can You Detect Compromised Credentials?
Detection is the critical first step. You can’t protect credentials you don’t know are compromised.
Dark web monitoring is the continuous process of scanning criminal marketplaces, hacker forums, and threat actor channels for your organization’s exposed credentials. Unlike one-time breach checks, it provides ongoing surveillance to detect leaked credentials before attackers can exploit them.
Dark web monitoring scans criminal marketplaces, hacker forums, and infostealer channels for your organization’s credentials. Effective monitoring covers not just public breach databases but private channels where fresh credentials first appear.
Behavioral analytics identify when account activity deviates from normal patterns. Impossible travel, unusual access times, and anomalous data access all indicate potential compromise.
Threat intelligence feeds provide context about active credential threats. They identify which credential dumps are circulating, which infostealers are active, and which organizations are being targeted.
Endpoint detection can catch infostealer infections before credentials leak. Modern EDR tools recognize infostealer behavior patterns and can stop credential theft in progress.
How Should You Respond to Compromised Credentials?
When you detect compromised credentials, speed matters. Every hour of delay gives attackers more time to exploit access.
Immediately reset the password. Don’t wait. Force password resets for all affected accounts. Use a clean device if the original may be infected.
Revoke all active sessions. Changing the password isn’t enough if attackers have session tokens. Invalidate all existing sessions so anyone using stolen cookies gets kicked out.
Investigate the source. Determine how credentials were compromised. Was it an infostealer infection? A phishing attack? A third-party breach? Understanding the source helps you identify other potentially compromised accounts.
Clean the infected devices. If malware was involved, don’t enter new credentials until the device is clean. An active infostealer will capture the new password immediately after you set it.
Assess the scope. Review logs to understand what attackers accessed. Look for data exfiltration, configuration changes, new accounts created, and lateral movement attempts.
Monitor for follow-on attacks. Compromised credentials often precede larger attacks. Watch for unusual activity on related accounts, lateral movement attempts, and signs of persistent access.
Preventing Credential Compromise
Prevention beats response every time. Here’s how to stop credentials from becoming compromised.
Deploy dark web monitoring. Detect leaked credentials before attackers can use them. Dark web monitoring finds your credentials in infostealer logs or dark web listings so you can reset them before exploitation occurs.
Implement phishing-resistant MFA. Hardware security keys and passkeys provide the strongest protection. Microsoft research shows MFA blocks 99.9% of automated credential attacks. CISA recommends phishing-resistant MFA for all critical accounts.
Strengthen endpoint protection. Infostealers are the primary source of compromised credentials. EDR tools that detect and block infostealer behavior prevent credential theft at the source.
Use password managers. Unique, strong passwords for every account eliminate the password reuse problem. Enterprise password managers also prevent credentials from being stored in browsers where infostealers can harvest them.
Train employees. Phishing and social engineering succeed because people aren’t prepared. Regular security awareness training helps employees spot attacks before they click.
The threat from compromised credentials isn’t going away. Organizations that detect and respond quickly limit the damage. Those that don’t give attackers more time to exploit their access.
Take the first step. Check if your credentials are already compromised.
Compromised Credentials FAQ
Compromised credentials are usernames, passwords, session tokens, or API keys that have been stolen and are actively being exploited or at immediate risk of exploitation. Unlike leaked credentials that may sit dormant in breach dumps, compromised credentials are in the hands of attackers ready to use them.
Leaked credentials are exposed to unauthorized parties but may never be used. Compromised credentials are actively exploited or at immediate risk. Think of leaked credentials as potential threats and compromised credentials as active threats requiring immediate response.
Signs include unexpected MFA prompts, impossible travel alerts, unauthorized account changes, and your credentials appearing in infostealer channels or dark web marketplaces. Dark web monitoring can detect compromised credentials before attackers use them.
Immediately reset the password, revoke all active sessions, and enable phishing-resistant MFA. Investigate how the compromise occurred to identify other potentially affected accounts. If malware was involved, clean or reimage the infected device before entering new credentials.
Credentials become compromised through infostealer malware, phishing attacks, third-party data breaches, credential stuffing, and session hijacking. Infostealers are particularly dangerous because they capture both passwords and session tokens that bypass MFA.
No. Once credentials are compromised, they cannot be recovered or made safe again. The only option is mitigation: reset the password, revoke sessions, and monitor for follow-on attacks. This is why early detection through credential monitoring is critical.