Cookie Poisoning

Definition of Cookie Poisoning

Cookie poisoning is a technique used by cyber attackers to manipulate, forge, or alter cookies, which are small files that websites store on users’ devices for various purposes like tracking and personalization. The aim of this malicious activity is to gain unauthorized access to a user’s account or sensitive information. Such attacks exploit vulnerabilities in cookie handling and may lead to identity theft or unauthorized access to web applications.


The phonetic pronunciation of the keyword “Cookie Poisoning” is:Kʊki pɔɪzənɪŋ

Key Takeaways

  1. Cookie Poisoning is a method where an attacker manipulates, forges, or decrypts cookies to gain unauthorized access to a user’s personal data or system resources.
  2. Preventing Cookie Poisoning involves the use of secure data transfers (HTTPS), adequately hashing and encrypting sensitive cookie data, and setting appropriate HttpOnly and SameSite attributes.
  3. Being aware of Cookie Poisoning threats is essential for maintaining website security and protecting user privacy, as attackers may use stolen cookie information to impersonate users, alter user preferences, or gain access to sensitive data.

Importance of Cookie Poisoning

Cookie poisoning is an important technology term because it refers to a malicious technique used by attackers to manipulate, alter, or forge the content of cookies in order to gain unauthorized access to sensitive information or user accounts.

By understanding and addressing cookie poisoning, developers and security professionals can enhance the security of web applications and protect user data from potential breaches.

Being aware of this term helps in the implementation of countermeasures, such as encryption and secure transmission of cookies, to mitigate the risk of attacks and ensure the privacy and safety of users in the digital world.


Cookie poisoning is a malicious technique utilized by cyber criminals to manipulate or modify the contents of a cookie, which is a small piece of data stored on a user’s device, with the objective of stealing sensitive information or gaining unauthorized access to a user’s online accounts. This tactic is particularly dangerous as it exploits a user’s trust in the legitimacy of a cookie when using a web application.

To better grasp the purpose of cookie poisoning, it is essential to understand that cookies play a crucial role in retaining a user’s preferences and login details, making web browsing more convenient and personalized. By altering the data in a cookie, a hacker can gain unauthorized access to user accounts, bypass security restrictions, or even impersonate a user online, ultimately resulting in a breach of privacy or possible data theft.

Typically, an attacker carries out cookie poisoning by employing various techniques such as intercepting data transfers between a user’s browser and a web server through methods like eavesdropping, session hijacking, or man-in-the-middle (MITM) attacks. Additionally, attackers may utilize cross-site scripting (XSS) vulnerabilities to inject malicious scripts into a trusted webpage, which in turn manipulate the cookie’s content.

Once the cookie is poisoned, a cyber criminal can exploit the user’s compromised session for their own benefit, which may include illegal financial transactions, stealing personal data, or even spreading malware to other devices. As a result, users and businesses should prioritize robust security measures, such as using HTTPS encryption, implementing secure cookie flags, and adopting strong authentication methods, to minimize the risks associated with cookie poisoning and safeguard their sensitive information.

Examples of Cookie Poisoning

Cookie poisoning, also known as cookie manipulation or tampering, is a technique used by cybercriminals to exploit and manipulate user data stored in cookies. Here are three real-world examples of cookie poisoning:

E-Commerce Attack: In 2015, British telecom company TalkTalk experienced a significant data breach, which allowed hackers to steal sensitive customer data. Part of the attack included cookie poisoning, as the hackers tampered with users’ session cookies to impersonate their identities and gain unauthorized access to customer accounts.

Social Media Hijacking: In 2013, a critical vulnerability was discovered in Facebook’s app integration system. This vulnerability allowed hackers to poison users’ cookies and gain access to private messages, photos, and other sensitive data. By exploiting this security flaw, an attacker could impersonate the user, send malicious messages, and potentially take over their account. After discovering the vulnerability, Facebook promptly fixed the issue and rewarded the security researcher who reported it with a bug bounty.

Online Banking Fraud: Although not specific to one incident, cookie poisoning has also been used to target online banking systems. Cybercriminals manipulate cookies to bypass the client’s authentication process, allowing them to access a user’s account and conduct unauthorized financial transactions. In the early 2000s, several online banks faced cookie poisoning attacks, leading them to implement advanced security measures, such as two-factor authentication, to avoid future attempts of cookie tampering.

FAQ – Cookie Poisoning

What is cookie poisoning?

Cookie poisoning refers to the manipulation or modification of cookie data stored in a user’s browser by a cybercriminal. This technique is used to gain unauthorized access to sensitive information, bypass security measures, and perform various malicious activities.

How does cookie poisoning work?

Cookie poisoning works by intercepting, altering, or forging a user’s cookie data. Cybercriminals may use different methods, such as exploiting security vulnerabilities, cross-site scripting (XSS) attacks, or man-in-the-middle attacks, to modify the contents of the cookie. Once the cookie has been tampered with, the attacker gains unauthorized access to the user’s account and sensitive information.

What are the common types of cookie poisoning attacks?

Common types of cookie poisoning attacks include session hijacking, cross-site scripting (XSS), and man-in-the-middle attacks. Session hijacking involves stealing a user’s session cookie to gain unauthorized access to their account, while XSS exploits vulnerabilities in web applications to inject malicious scripts that tamper with cookie data. Man-in-the-middle attacks involve intercepting and altering a user’s cookie data during transmission between their browser and the web server.

How can I protect my web application against cookie poisoning?

To protect your web application against cookie poisoning, implement secure coding practices and follow the best security measures. These include using secure cookies with the HttpOnly and Secure flags, validating and sanitizing user input, implementing proper access controls, using encryption to protect data transmission, and regularly updating and patching your web application to address security vulnerabilities.

How can users protect themselves from cookie poisoning?

Users can protect themselves from cookie poisoning by following good security practices such as keeping their browsers and operating systems up-to-date, using strong, unique passwords for different accounts, enabling two-factor authentication (2FA) when available, avoiding public Wi-Fi networks for sensitive transactions, and being cautious about the websites they visit and the links they click on.

Related Technology Terms

  • Session Hijacking
  • Cross-Site Scripting (XSS)
  • Secure Sockets Layer (SSL)
  • Man-in-the-Middle Attack
  • Cookie Encryption

Sources for More Information


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