3,455,960 Plaintext Passwords Were Just Dumped on Telegram

In April 2023, HEROIC analysts identified a massive stealer log file labeled "Fresh Yahoo Good Base" that was uploaded to a public Telegram channel. The collection contained 3,455,960 records extracted from compromised devices, each record consisting of an email address, a plaintext password, and the URL of the service where the credentials were captured. Focused primarily on Yahoo-related accounts, this is one of the larger single-source stealer log dumps targeting a major email provider to appear on Telegram that year.

Why Plaintext Passwords Are the Worst-Case Scenario

In most data breaches, passwords are at least partially protected by hashing algorithms that make them difficult to reverse. That is not the case here. Every single password in the Fresh Yahoo Good Base collection is stored in plaintext, exactly as the victim originally typed it. There is no decryption step, no hash to crack, and no time delay before an attacker can use these credentials.

For nearly 3.5 million people, this means their passwords were weaponized the instant the file appeared on Telegram. Attackers equipped with credential stuffing tools can begin testing these login pairs against Yahoo Mail, Yahoo Finance, Flickr, and any other service within minutes of downloading the dump. The scale of immediate exposure is staggering.

What Was Exposed in the Fresh Yahoo Good Base Dump

• Email Addresses — Primarily Yahoo-associated email accounts, but also addresses from other providers that victims used to log into Yahoo-linked services, giving attackers verified contact points for phishing and identity theft.
• Plaintext Passwords — Fully readable passwords with no encryption or hashing, making every credential in the dump ready for immediate exploitation across any service where the same password was reused.
• URLs — The specific login pages and web services where each credential was captured, providing attackers with a detailed map of each victim's online activity and enabling targeted attacks on their most valuable accounts.

Why 3.4 Million Yahoo Credentials Represent a Massive Attack Surface

Yahoo remains one of the most widely used email platforms in the world, with hundreds of millions of active users. A stealer log dump of this size targeting Yahoo accounts creates an enormous attack surface. Credential stuffing operations thrive on volume: the more credential pairs an attacker has, the higher their success rate, even when only a small percentage of passwords are still active.

The danger multiplies because Yahoo email accounts often serve as recovery addresses for other services. An attacker who gains access to a Yahoo inbox can initiate password resets on banking sites, social media platforms, cloud storage, and workplace applications. A single compromised Yahoo account can become the gateway to an entire digital identity.

Research from multiple cybersecurity firms indicates that credential stuffing attacks succeed against 0.1% to 2% of targeted accounts. Applied to 3.4 million records, that translates to potentially thousands or tens of thousands of successful account takeovers from this single dump alone.

How Stealer Logs Siphon Credentials From Personal Devices

The Fresh Yahoo Good Base collection was not the result of a breach at Yahoo's servers. Instead, it was assembled from infostealer malware running on individual users' computers and phones. Malware families such as RedLine, Raccoon, Vidar, and Aurora infect devices through malicious email attachments, fake software downloads, and compromised websites.

Once installed, these infostealers operate silently in the background, extracting saved passwords from every browser on the device, logging keystrokes as users type new passwords, and capturing session cookies and autofill data. The harvested credentials are compiled into structured log files and uploaded to command-and-control servers operated by the malware's creators.

From there, the logs are sold, traded, or freely distributed through Telegram channels and underground forums. The "Fresh" label on this collection suggests the data was recent at the time of upload, increasing its value to attackers because the passwords were more likely to still be active and unchanged.

Check If Your Credentials Appear in This Leak

With 3,455,960 records in this dump, the likelihood of any given Yahoo user appearing in the dataset is meaningful. HEROIC provides a free breach scanner that checks your email address against more than 400 billion compromised records, including stealer log collections like the Fresh Yahoo Good Base.

Search your email to find out if your credentials have been exposed. If you find a match, change your Yahoo password immediately along with any other account that shares the same password. Enable two-factor authentication on your Yahoo account and every other critical service, and adopt a password manager to generate and store unique passwords for each account you use.