How One Hacker Banned Thousands of Call of Duty Players

In October, Activision announced that a bug in its anti-cheat system had wrongly flagged and banned a “small number” of Call of Duty players. But behind the scenes, the story ran much deeper. According to a hacker named Vizor, who claimed responsibility, thousands of players were wrongfully banned through this flaw, exploiting a weak point in the Ricochet anti-cheat system that was meant to protect fair players.

The Exploit and How It Worked

The Ricochet anti-cheat system, introduced by Activision in 2021, scans a player’s device for specific “signatures” or strings associated with cheats, such as terms like “Trigger Bot.” However, Vizor discovered that simply sending a private message with one of these flagged terms could trigger an automatic ban on the recipient’s account. This meant that any player could be unfairly flagged as a cheater if they received a message containing a “signature” keyword.

Vizor even tested this on themselves, sending a flagged message and confirming the resulting ban. They then automated the process to scale up the impact: by using a script to join games, send a flagged message, leave, and repeat, they managed to ban countless players automatically, without lifting a finger.

A History of Hacks and Cheats in Online Games

The gaming industry has long struggled with hackers who exploit flaws to gain unfair advantages. Cheat developers sell their programs to players looking for an edge, creating a massive market with millions of dollars at stake. Game companies respond by hiring cybersecurity experts to create and update anti-cheat systems.

Activision’s Ricochet was designed to protect the game at the kernel level—a deep integration intended to prevent even the most advanced cheats from bypassing it. Unfortunately, the flaw exploited by Vizor turned the system’s own mechanisms against its players, allowing Vizor to target random players, including some high-profile video game streamers.

Why This Happened

According to Vizor, Ricochet’s design relied on scanning for specific ASCII strings in memory, a straightforward method but one prone to false positives. By embedding these flagged keywords into private messages, Vizor weaponized the system against innocent players.

This is a significant lesson in security design. As one former Activision employee noted, relying on memory scans for specific keywords can be easily manipulated. With more sophisticated pattern recognition or context-aware scanning, such a loophole could have been prevented. However, Activision’s approach left them vulnerable, exposing thousands of players to unjust bans based on keyword detection alone.

Activision’s Response and Takeaways

Activision did fix the vulnerability, though it only came to their attention after Zebleer, a cheat developer and acquaintance of Vizor, disclosed the exploit publicly. This led to the reversal of bans for affected players, including some well-known streamers who had taken to social media about their bans.

The case emphasizes the need for robust cybersecurity in gaming. Basic keyword detection for cheats, while a common approach, opens systems to exploitation by savvy hackers. Companies need to continually evolve their anti-cheat measures and strengthen safeguards to prevent exploitation.

This incident shines a light on the complex challenge of maintaining fairness in online gaming. As hackers continue to innovate, anti-cheat technology must evolve to anticipate and prevent new forms of abuse. While Activision resolved this issue, the gaming community remains a battleground where cybersecurity plays an increasingly central role.