Anatomy of a Breach

Anatomy of a Breach: Steam — 35 Million Gamers' Data Compromised

> series: anatomy_of_a_breach —— part: 035 —— target: steam_valve —— accounts: 35,000,000 —— data: credentials_payment_info<span class="cursor-blink">_</span>_

Hedgehog Security 30 November 2011 11 min read

35 million gamers. Usernames, passwords, and payment data.

On 10 November 2011, Valve Corporation's Gabe Newell posted a message to the Steam community forums disclosing that hackers had breached the Steam platform and gained access to a database containing the personal information of approximately 35 million registered users. The compromised data included usernames, hashed and salted passwords, email addresses, billing addresses, and encrypted credit card information. The breach was discovered during the investigation of a separate DDoS attack on the Steam forums.

While Valve stated that the password hashing and credit card encryption should protect users from immediate exploitation, the company advised all users to change their passwords and monitor their credit card statements for suspicious activity. The breach followed the devastating Sony PlayStation Network hack by seven months, establishing that gaming platforms — with their enormous user bases, stored payment details, and valuable digital assets — were firmly in the crosshairs of attackers.


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Why gaming is a high-value target.

Massive User Bases
Steam had 35 million registered users in 2011; by 2025, that number exceeds 130 million monthly active users. Gaming platforms aggregate enormous volumes of personal data, credentials, and payment information — making them attractive targets for both data theft and credential-stuffing attacks.
Stored Payment Data
Gaming platforms store credit card details for recurring purchases, microtransactions, and digital content. The Steam breach exposed encrypted credit card data. Our <a href="/penetration-testing/pci-dss">PCI DSS penetration testing</a> assesses the security of stored payment data.
Digital Asset Value
Gaming accounts contain valuable digital assets — game libraries, in-game items, and virtual currencies that can be resold. Account takeover is not just a privacy concern but a financial one. Strong authentication — including the Steam Guard MFA system that Valve introduced post-breach — is essential.
Credential Reuse Risk
Gamers, like all users, reuse passwords across services. A compromised Steam credential can be used to attack the same user's email, banking, or social media accounts. The <a href="/blog/anatomy-of-a-breach-2010-year-review">Gawker credential cascade</a> demonstrated this risk. MFA — mandated by <a href="/cyber-essentials">Cyber Essentials Danzell</a> — breaks the credential reuse chain.

Hashed passwords and encrypted cards limited the damage.

Unlike Sony (which stored passwords with inadequate hashing) and Sony Pictures (which stored passwords in plaintext), Valve had hashed and salted user passwords and encrypted credit card data. This meant that while the database was exfiltrated, the data was not immediately usable by the attackers. Proper password storage and payment data encryption are exactly the controls our web application testing verifies — and the controls whose absence made the Sony breaches so catastrophic.

Post-breach, Valve introduced Steam Guard — an email-based and later mobile-based two-factor authentication system — establishing MFA as a gaming industry standard. For organisations handling large user bases and stored credentials, our penetration testing verifies password storage security, our PCI DSS assessments evaluate payment data protection, and SOC in a Box monitors for credential theft and account takeover attempts. UK Cyber Defence provides incident response when a platform breach is discovered.


35 million accounts is a lot to lose. How secure is your platform?

Our <a href="/penetration-testing/web-application">web application testing</a> assesses password storage, payment data protection, and platform security. <a href="/cyber-essentials">Cyber Essentials</a> establishes baseline authentication controls. <a href="https://www.socinabox.co.uk">SOC in a Box</a> monitors for credential theft.

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