Credential Theft: When Stolen Access Goes Undetected for Months

The Silent Risk: Credentials on the Darknet

One of the most common – and simultaneously least visible – attack vectors is the misuse of stolen credentials. Compromised passwords, tokens, and session cookies reach criminals through various routes: phishing, infostealer malware running on employees' private or business devices, or data breaches at external services where employees use the same credentials as in the corporate context.

The key factor: weeks or months often pass between credential theft and active use. Credentials are traded on the darknet, tested, and sometimes resold multiple times before an attacker uses them for targeted access. During this time, action would be possible – but only if you know the credentials are compromised.

How Infostealers Work and Why They Are So Dangerous

Infostealers are a particularly insidious type of malware that has increased massively in recent years. They are typically distributed via fake software downloads, phishing, or exploit kits and collect credentials in the background from browsers, email clients, VPN clients, and other applications. The collected data is automatically transmitted to a command-and-control server and then sold to darknet marketplaces.

Particularly problematic: infostealers frequently run on private devices used for home office or remote access. The employee often notices nothing, the device continues to function normally – and credentials for corporate VPNs, cloud services, or SaaS platforms are then circulating on the darknet.

What Credential Monitoring Can Achieve

Systematic credential leak monitoring continuously analyzes darknet sources – marketplaces, forums, paste sites, Telegram channels – for credentials associated with corporate domains. The result: concrete warnings when employee credentials have been exposed, including information about which leak or infostealer the data was stolen through.

This early warning enables targeted measures: password reset for affected accounts, review of possible unauthorized access during the relevant period, and if necessary, forensics of the affected device.

Note: This article is for general information purposes and does not replace an individual security assessment.