Stolen Browser Cookies: How Session Hijacking Threatens Crypto Accounts

A strong password and two-factor authentication are essential for protecting a cryptocurrency exchange account, but an attacker may target something different: the browser session created after a successful login. If malware steals an active session cookie, a criminal may try to reuse it and impersonate the authenticated user. This guide explains how cookie theft and session hijacking work, why crypto users should take the threat seriously and how NordVPN fits into a layered security plan.

Last reviewed: August 27, 2026. Security features, exchange controls and malware techniques change over time. Confirm current instructions with NordVPN and your exchange. This article is educational and does not guarantee protection against every attack.

What are browser cookies?

A cookie is a small piece of data that a website asks a browser to store. Cookies can remember language choices, shopping-cart contents, analytics identifiers and login state. They are not automatically malicious; modern websites rely on them for many ordinary functions.

After a user signs in, a service may issue a session cookie that tells the website the browser has already completed authentication. This prevents the user from entering a password on every page. The convenience also makes an active session valuable. Anyone able to reuse a valid session token may be treated as the logged-in user until the service rejects or expires it.

What is session hijacking?

Session hijacking is the unauthorized use of another person’s authenticated web session. Instead of guessing the password, the attacker attempts to obtain and replay the token that represents the existing login. Whether that attempt succeeds depends on the service’s defenses, the token’s validity and checks involving the device, location or browser.

For a crypto exchange account, the consequences can be serious. An intruder may inspect balances and identity data, modify security settings, create API credentials, place trades or attempt a withdrawal. Withdrawal allowlists, fresh-authentication requirements, device approval and risk controls can limit the damage, but users should not assume every sensitive action will always require a new password or 2FA code.

What NordVPN’s stolen-cookie research found

NordVPN reported that researchers identified 52,389,324,619 stolen cookie records in historical infostealer data covering June 9, 2025 through June 8, 2026. This figure describes cookie records—not 52.4 billion unique victims, devices or infections. A single infected browser can contain many cookies.

The research associated almost four in five of the observed stolen cookies with three infostealer families: Lumma-C2, RedLine and Vidar. It also found large volumes of credentials, autofill entries and files in the broader dataset. That combination matters because a criminal may gain both an active session and contextual information that makes account takeover or targeted phishing easier.

The study was global and based on historical infostealer information analyzed through the NordStellar platform. Its totals should not be interpreted as a complete measurement of every stolen cookie worldwide. They nevertheless illustrate why browser data has become a high-value target.

How infostealers collect session data

An infostealer is malware designed to extract valuable information from an infected device. Depending on its capabilities and permissions, it may collect browser cookies, saved passwords, autofill data, cryptocurrency wallet information, files, screenshots and device details.

Common infection paths include:

• Fake wallet applications or browser extensions.
• Cracked software, game cheats and untrusted download sites.
• Malicious advertisements and fake software-update prompts.
• Phishing links delivered through email, messaging apps or social media.
• Infected attachments and counterfeit support tools.
• Search advertisements impersonating a wallet, exchange or VPN provider.

Crypto users are attractive targets because one compromised computer may reveal exchange sessions, email access, saved credentials and wallet-related activity. The attacker can combine these fragments instead of relying on a single weakness.

Can stolen cookies bypass 2FA?

Two-factor authentication protects the login process by requiring an additional factor after the password. A stolen session token represents a login that may already have passed those checks. Reusing it can therefore bypass the initial sign-in screen on services that do not sufficiently bind sessions to the original device or reauthenticate sensitive actions.

This does not make 2FA useless. It remains one of the most important account protections and can stop password-only attacks. Exchanges may also require a new code for withdrawals or security changes. The lesson is that 2FA should be combined with clean devices, session monitoring, withdrawal controls and careful browser use.

Warning signs of a compromised crypto session

• Unknown devices, locations or sessions appear in account security settings.
• You receive login, API-key or withdrawal notifications you did not initiate.
• Orders, conversions, address-book entries or account changes are unfamiliar.
• Your email contains unexpected password-reset or device-confirmation messages.
• The exchange repeatedly logs you out without an obvious explanation.
• Browser behavior changes, security tools are disabled or unknown extensions appear.
• A security product warns that credentials or session information may be exposed.

A single sign is not proof of cookie theft, but unexpected account activity should be treated as urgent. Use a different trusted device to begin recovery if the normal computer may be infected.

What to do if a session cookie may be stolen

1. Isolate the potentially infected device

Disconnect it from networks and stop using it for exchange, email or wallet activity. Do not change important passwords on a device that may still contain an active infostealer.

2. End all active sessions

From a trusted device, use the exchange’s security settings to log out every session and remove unknown devices. Changing a password alone may not always invalidate every active token immediately, so explicitly use the global sign-out option when available.

3. Secure the email account first

Email often controls password resets and device approvals. Change its password to a new unique value, end other sessions, verify recovery details and enable phishing-resistant MFA where supported.

4. Reset exchange credentials and controls

Change the exchange password, replace compromised 2FA secrets if necessary, revoke unfamiliar API keys and review withdrawal addresses. Enable a withdrawal allowlist, anti-phishing code and fresh-login notifications when the platform provides them.

5. Review activity and contact official support

Check logins, trades, withdrawals, API activity and security changes. Save evidence such as timestamps and transaction identifiers. Open support only through the verified exchange website or application; scammers often impersonate recovery agents.

6. Scan, rebuild and update

Use current reputable security tools to investigate the device. For a confirmed or strongly suspected infostealer infection, a clean operating-system reinstall may provide more confidence than deleting one detected file. Update the operating system and applications, reinstall browser extensions only from verified sources and restore documents cautiously.

How to reduce cookie-theft risk

• Use a dedicated browser profile for exchanges and financial services.
• Install as few browser extensions as possible and audit their permissions.
• Never install cracked applications, unofficial wallets or unverified trading tools.
• Bookmark official exchange domains instead of relying on advertisements or messages.
• Keep the browser, operating system and security software updated.
• Use unique passwords stored in a reputable password manager.
• Prefer an authenticator app, passkey or hardware security key over SMS where supported.
• Regularly review active sessions, devices, API keys and withdrawal addresses.
• Keep long-term assets in appropriately secured self-custody rather than an active trading account.
• Separate everyday browsing and experimental crypto activity from high-value accounts.

What NordVPN can and cannot protect

NordVPN encrypts supported traffic between a device and its VPN server, which is useful on public Wi-Fi and limits what the local network or internet provider can observe about destinations. A VPN can also replace the public IP visible to websites with the VPN server’s address.

That network protection does not prevent malware already running on a device from reading data the user or browser can access. A VPN cannot make a stolen session harmless, recover cryptocurrency, verify every download or replace exchange security controls.

NordVPN also offers additional security capabilities that vary by subscription and platform. Its next-generation antivirus includes a hijacked-session alert intended to warn when session cookies appear in known stolen-cookie datasets. An alert is a reason to end sessions, change credentials and scan the device—not proof that the threat has already been removed.

Crypto account security checklist

Final thoughts

Cookie theft shows why crypto security cannot stop at passwords. An authenticated browser session is valuable, and an infostealer can collect it alongside credentials and other personal information. Strong MFA remains necessary, but users should also protect the device that holds the session and monitor what happens after login.

Use NordVPN as one network-security layer, not as a promise of complete protection. Combine it with clean software, verified domains, restricted browser extensions, exchange alerts, withdrawal controls and deliberate separation of trading funds from long-term holdings.

Official research reference: NordVPN — Cookies: Research reveals 52.4B stolen cookies in one year. The source reports aggregate cookie records from an observed dataset, not a count of unique victims.