Description

A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks.

An http parameter may contain a URL value and could cause the web application to redirect the request to the specified URL. By modifying the URL value to a malicious site, an attacker may successfully launch a phishing scam and steal user credentials. Because the server name in the modified link is identical to the original site, phishing attempts have a more trustworthy appearance.

Phishing is a general term for deceptive attempts to coerce private information from users that will be used for identity theft.

Modes of Introduction:

– Architecture and Design

Likelihood of Exploit: Low

Related Weaknesses

CWE-610
CWE-610

Consequences

Access Control: Bypass Protection Mechanism, Gain Privileges or Assume Identity

The user may be redirected to an untrusted page that contains malware which may then compromise the user’s machine. This will expose the user to extensive risk and the user’s interaction with the web server may also be compromised if the malware conducts keylogging or other attacks that steal credentials, personally identifiable information (PII), or other important data.

Access Control, Confidentiality, Other: Bypass Protection Mechanism, Gain Privileges or Assume Identity, Other

The user may be subjected to phishing attacks by being redirected to an untrusted page. The phishing attack may point to an attacker controlled web page that appears to be a trusted web site. The phishers may then steal the user’s credentials and then use these credentials to access the legitimate web site.

Potential Mitigations

Phase: Implementation

Description: 

Phase: Architecture and Design

Description: 

Use an intermediate disclaimer page that provides the user with a clear warning that they are leaving the current site. Implement a long timeout before the redirect occurs, or force the user to click on the link. Be careful to avoid XSS problems (CWE-79) when generating the disclaimer page.

Phase: Architecture and Design

Description: 

Phase: Architecture and Design

Description: 

Ensure that no externally-supplied requests are honored by requiring that all redirect requests include a unique nonce generated by the application [REF-483]. Be sure that the nonce is not predictable (CWE-330).

Note that this can be bypassed using XSS (CWE-79).

Phase: Architecture and Design, Implementation

Description: 

Phase: Operation

Effectiveness: Moderate

Description: 

Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.

An application firewall might not cover all possible input vectors. In addition, attack techniques might be available to bypass the protection mechanism, such as using malformed inputs that can still be processed by the component that receives those inputs. Depending on functionality, an application firewall might inadvertently reject or modify legitimate requests. Finally, some manual effort may be required for customization.

CVE References

• CVE-2005-4206
  • URL parameter loads the URL into a frame and causes it to appear to be part of a valid page.

• CVE-2008-2951
  • An open redirect vulnerability in the search script in the software allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a URL as a parameter to the proper function.

• CVE-2008-2052
  • Open redirect vulnerability in the software allows remote attackers to redirect users to arbitrary web sites and conduct phishing attacks via a URL in the proper parameter.