Fraudsters are increasingly targeting digital session cookies to gain unauthorized access to online accounts, according to cybersecurity experts. Session hijacking, a form of cyber fraud, involves stealing these cookies—small data files that store a user’s login information during an active session—to impersonate legitimate users without needing their passwords.

When a user logs into a website, such as a bank portal, the site places a session cookie on their device, allowing the user to navigate webpages without repeatedly entering login credentials. These cookies remain valid until the user logs out or the session expires. However, security specialists warn that if the session remains open or the user selects options like “remember me,” fraudsters can exploit the vulnerability by stealing the session cookie before it is deactivated.

Marijus Briedis, chief technology officer at NordVPN, explained that session cookies function like digital keys that keep doors open once unlocked. If a hacker steals an active cookie, they effectively gain the same access rights as the user, bypassing passwords, login alerts, and sometimes even multi-factor authentication (MFA).

Cookie theft typically occurs when malware infects a user’s device. Once installed, malicious software extracts active session cookies from browsing databases and sends them to attackers. This method allows criminals to silently take over accounts without triggering obvious security warnings.

Victims may remain unaware they have been compromised until they detect unauthorized activity. For instance, attackers may use hijacked social media or email accounts to carry out scams, access bank accounts to make fraudulent transactions, or manipulate online shopping orders and payment details.

To mitigate the risk of session hijacking, experts advise users to be cautious about installing browser extensions and software, as these are common vectors for malware. Signs of infection include poor device performance, rapid battery drain, frequent crashes, and unusual browser behavior like redirects or altered homepages.

Using unsecured public Wi-Fi networks to access sensitive accounts also presents risks, although the likelihood of cookie theft through this method is relatively low. Importantly, users should always manually log out of accounts rather than simply closing browser tabs, as this action invalidates session cookies and prevents their reuse.

Additional precautions include employing dedicated password managers instead of storing passwords within browsers, regularly clearing cookies, and enabling multi-factor authentication wherever possible. In the event of suspected compromise, running antivirus scans, logging out of all devices, changing passwords, and promptly notifying banks of suspicious transactions are recommended steps.

These security measures, while not foolproof, provide enhanced protection against increasingly sophisticated session hijacking attacks targeting the digital keys that safeguard online accounts.