Overview
CVE-2021-47663 is a critical vulnerability that enables an unauthenticated remote attacker to guess a valid session ID, allowing them to impersonate a user and gain full access to the system. With the rise of remote work and digital spaces, the security of online systems is paramount. This vulnerability affects any system that has improperly implemented JSON Web Tokens, posing a significant threat to data integrity and system security. The severity of the vulnerability is underscored by its CVSS severity score of 8.1, which points to its potential for serious damage if left unaddressed.
Vulnerability Summary
CVE ID: CVE-2021-47663
Severity: Critical (CVSS: 8.1)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System compromise and potential data leakage
Affected Products
No phone number, email, or personal info required.
Product | Affected Versions
[Product 1] | [All versions with improper JWT implementation]
[Product 2] | [All versions with improper JWT implementation]
How the Exploit Works
The exploit takes advantage of an improper implementation of JSON Web Tokens (JWTs). JWTs are an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. However, if the JWTs are implemented improperly, the digital signature can be compromised.
An attacker can use this vulnerability to guess a valid session ID. Once the session ID is guessed, it allows the attacker to impersonate a user, which in turn grants them full access to the system. This can lead to system compromise or potential data leakage, putting sensitive data at risk.
Conceptual Example Code
A potential exploit might look something like this, where the attacker sends a malicious request to a vulnerable endpoint:
POST /vulnerable/endpoint HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "session_id": "guessed_or_stolen_session_id" }In this conceptual example, the “guessed_or_stolen_session_id” represents a session ID that the attacker has either guessed or stolen, allowing them to impersonate a user and gain unauthorized access to the system.
Mitigation
To mitigate this vulnerability, apply the patch provided by the vendor as soon as possible. If a patch is not immediately available or cannot be applied immediately, use a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) as a temporary measure to detect and prevent exploitation attempts. Additionally, ensure that JSON Web Tokens are properly implemented as per the guidelines in RFC 7519.