Session fixation attacks take advantage of the way web applications manage session identifiers. Here’s how a session fixation attack typically
works:
- When a user visits a website or logs in, a session is created for them.
- This session is assigned a unique session identifier, stored in a cookie, in local storage, or through URL parameters.
- In a session fixation attack, an attacker tricks a user into using a predetermined session identifier controlled by the attacker. For example,
the attacker sends the victim an email containing a link with this predetermined session identifier.
- When the victim clicks on the link, the web application does not create a new session identifier but uses this identifier known to the
attacker.
- At this point, the attacker can hijack and impersonate the victim’s session.
What is the potential impact?
Session fixation attacks pose a significant security risk to web applications and their users. By exploiting this vulnerability, attackers can gain
unauthorized access to user sessions, potentially leading to various malicious activities. Some of the most relevant scenarios are the following:
Impersonation
Once an attacker successfully fixes a session identifier, they can impersonate the victim and gain access to their account without providing valid
credentials. This can result in unauthorized actions, such as modifying personal information, making unauthorized transactions, or even performing
malicious activities on behalf of the victim. An attacker can also manipulate the victim into performing actions they wouldn’t normally do, such as
revealing sensitive information or conducting financial transactions on the attacker’s behalf.
Data Breach
If an attacker gains access to a user’s session, they may also gain access to sensitive data associated with that session. This can include
personal information, financial details, or any other confidential data that the user has access to within the application. The compromised data can
be used for identity theft, financial fraud, or other malicious purposes.
Privilege Escalation
In some cases, session fixation attacks can be used to escalate privileges within a web application. By fixing a session identifier with higher
privileges, an attacker can bypass access controls and gain administrative or privileged access to the application. This can lead to unauthorized
modifications, data manipulation, or even complete compromise of the application and its underlying systems.
