DIGITAL LIFE

Forget santa, HP warns hackers are coming for your cookies
HP Threat Research(threatresearch.ext.hp.com) just issued a new security report detailing a growing trend by attackers towards hijacking session cookies as an alternative means to tried-and-true credential theft. The reason hackers are finding a bigger appetite for sessions cookies is because today's hybrid work environment has led to changes that make stealing cookies more appealing than the old way of doing things.
Citing its 2025 Work Relationship Index, HP says one in five employees now work flexibly across office, home, and mobile environments. Meanwhile, enterprises are increasingly moving their core infrastructures to the cloud for the convenience of managing IT chores with a web browser, rather than utilizing on-premise domain controllers. This has led to a change in the way threat attackers breach organizations.
"Rather than steal credentials, attackers are now increasingly focusing on stealing authentication cookies. In this type of attack, a threat actor no longer needs to steal credentials or bypass MFA. Instead, they simply need the browser cookie that proves the target user (e.g. a system administrator) is logged in. Once they have it, they effectively have the privileges and access of that user," HP says.
This doesn't mean MFA (multi-factor authentication) is no longer important. HP notes that despite the draw of warm cookies, bad old fashioned credential theft is still popular. It's also preventable with MFA. However, organizations would be wide to also assess the risks inherent with today's hybrid work environments.
Whenever a user logs into a system, an authentication session is opened for that user and is used to keep the login active while interacting with the system. There are different ways of storing an open authentication system, such as locally on the user's device. However, storing sessions in the form of a cookie "is standard practice and used by most web applications," as it negates the need for manual session management. Therein lies the risk.
"If an attacker can obtain the authentication cookie, they can take over the active session and gain unauthorized access to a system. This gives the attacker the same access to the system as the initial user. So, if the user is a Microsoft Entra administrator, the attacker can gain critical permissions to an entire organization. In such a case, the attacker could weaken or bypass security controls, gain elevated privileges, or set up a persistent backdoor," HP warns.
Even worse, MFA offers absolutely no protection against this type of attack, since the threat actor has taken over the active session. And according to HP's data, token theft is the most common technique employed by hackers to bypass MFA and infiltrate Microsoft 365 services.
How is this done, though? HP says threat actors are using information stealers to swipe session cookies.
"Attackers infect an endpoint with malware that is capable of either directly taking over a session and injecting commands, or exfiltrating relevant active cookies from the system to an attacker-controlled server," HP explains.
HP's report goes on to highlight notable documented incidents of session cookie theft, including one that impacted Electronic Arts and resulted in hackers stealing 780GB of data. It also outlines preventative steps organizations can take, such as binding active sessions to a specific context, reducing how long sessions are active before needing to be validated again, and requiring re-authorization for sensitive actions such as adding a new administrator or changing passwords.
https://threatresearch.ext.hp.com/tracing-the-rise-of-breaches-involving-session-cookie-theft/
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