Stolen credentials are the easiest way into most organizations. Attackers no longer need to break in when they can log in with a valid username, a password and, increasingly, a session cookie copied from an infected laptop. Sophos found that 79% of ransomware attacks in 2026 started with compromised identities.
ACID’s credential leak monitoring watches the places where those credentials are bought, sold and shared, and alerts your team the moment logins tied to your organization appear. It is part of ACID’s dark web monitoring service and runs on the ACID Intelligence platform.
What credential leak monitoring covers
Credentials reach the underground through several routes, and each needs its own coverage:
- Infostealer logs. Malware such as RedLine, Lumma and Vidar copies saved passwords, cookies and autofill data from infected devices. The logs are sold in bulk on dark web markets and shared in Telegram channels, often within hours of infection.
- Combo lists. Large lists of email and password pairs compiled from older breaches and used for credential-stuffing attacks.
- Breach dumps. Databases stolen from third-party services where your employees or customers reused a work email.
- Access broker listings. Offers of VPN, RDP, Citrix or cloud console access to a named company, usually built on stolen credentials.
- Paste and file-sharing sites. Quick dumps of credentials posted to paste tools or shared over P2P and file lockers.
ACID monitors dark web markets and forums, deep web sources, paste tools, dump and leak sites, and major chat and messaging platforms around the clock. Keywords are set for each client — domains, subdomains, SSO portals, application names and priority accounts — and translated into the languages that matter for your risk surface.
Why infostealer logs change the picture
Traditional breach monitoring checks whether an email address appeared in a published breach. That still matters, but it misses the fastest-growing source of account takeover.
Infostealer logs are different in three ways:
- They are fresh. A log is usually for sale within days of the infection, while breach dumps can surface years later.
- They are plain text. Passwords are captured as the user typed them, so there is no hash to crack.
- They include sessions. Session cookies and tokens let an attacker reuse an authenticated browser session, which can bypass multi-factor authentication until the session is revoked.
An infected personal device that an employee also uses for work can expose corporate SSO, VPN, email and SaaS logins at once. Catching that log quickly is the difference between a forced password reset and an incident response.
How it works
Credential leak monitoring follows the same four stages as the rest of ACID’s service:
- Monitor. Automated crawlers collect new material from markets, forums, leak sites, paste tools and messaging channels 24/7/365.
- Detect. AI-assisted matching compares new material against your keywords and filters out noise, such as recycled combo lists you have already been told about.
- Alert. A real-time alert shows the affected account or domain, the source type, the date first seen and the data exposed (password, cookie, token or machine details). Updates follow as more information comes in.
- Mitigate. Your team resets passwords, revokes sessions, checks the affected device and looks for signs that the credentials were already used.
Example alerts
These anonymized examples show the kind of detail an alert carries:
- Critical: infostealer log with SSO session. A log from an infected device contains a valid session cookie for the client’s single sign-on portal, plus saved logins for email and a CRM. First seen on a dark web log market.
- High: VPN access offered. An access broker advertises VPN credentials for a company matching the client’s sector, size and region, with a sample showing the client’s domain.
- Medium: combo list mention. 1,200 email and password pairs using the client’s domain appear in a new combo list. Most match an older third-party breach; 40 are new.
Who needs credential leak monitoring
Every organization with users who log in to anything is exposed, but the risk is highest where one account opens a lot of doors:
- Banks and financial services, where customer account takeover leads straight to fraud. See financial services.
- Healthcare, where clinical systems and patient records sit behind shared logins. See healthcare.
- Organizations with remote access, where VPN and remote-desktop credentials are the most common initial access sold by brokers.
- SaaS and e-commerce businesses, where credential stuffing against customer accounts causes fraud, chargebacks and support load.
Credential monitoring vs. free breach lookups
Free lookup tools check a single email address against breaches that have been published and indexed. They are useful for individuals, but they do not cover infostealer logs sold in closed markets, access offers in messaging channels, or your whole domain at once, and they do not alert your SOC in real time.
ACID’s monitoring is tailored to your domains and applications, covers closed and fast-moving sources, and delivers alerts to your dashboard, email, SIEM/SOAR or API so resets can be automated. Read more in our guide to compromised accounts.
Get started
See what is already exposed with a free dark web scan, or talk to an analyst about adding credential leak monitoring to your program. Related capabilities include ransomware leak site monitoring, Telegram monitoring and brand impersonation monitoring.
“The earlier you see planning-stage activity, the more options you have—foil the attack, close the gap, or contain the blast radius before public disclosure.”