URL Redirection to Untrusted Site ('Open Redirect')ID: 601 | Date: (C)2012-05-14 (M)2022-10-10 | Type: weakness | Status: DRAFT | Abstraction Type: Variant |
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. Extended DescriptionAn 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. Likelihood of Exploit: Low to Medium Applicable PlatformsLanguage Class: Language-independentArchitectural Paradigm: Web-based Time Of Introduction - Architecture and Design
- Implementation
Related Attack Patterns Common Consequences Scope | Technical Impact | Notes |
---|
Access_Control | Bypass protection
mechanismGain privileges / 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_ControlConfidentialityOther | Bypass protection
mechanismGain privileges / assume
identityOther | 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. |
Detection Methods Name | Description | Effectiveness | Notes |
---|
Manual Static Analysis | Since this weakness does not typically appear frequently within a
single software package, manual white box techniques may be able to
provide sufficient code coverage and reduction of false positives if all
potentially-vulnerable operations can be assessed within limited time
constraints. | High | | Automated Dynamic Analysis | Automated black box tools that supply URLs to every input may be able
to spot Location header modifications, but test case coverage is a
factor, and custom redirects may not be detected. | | | Automated Static Analysis | Automated static analysis tools may not be able to determine whether
input influences the beginning of a URL, which is important for reducing
false positives. | | | Other | Whether this issue poses a vulnerability will be subject to the
intended behavior of the application. For example, a search engine might
intentionally provide redirects to arbitrary URLs. | | |
Potential Mitigations Phase | Strategy | Description | Effectiveness | Notes |
---|
Implementation | Input Validation | Assume all input is malicious. Use an "accept known good" input
validation strategy, i.e., use a whitelist of acceptable inputs that
strictly conform to specifications. Reject any input that does not
strictly conform to specifications, or transform it into something that
does.When performing input validation, consider all potentially relevant
properties, including length, type of input, the full range of
acceptable values, missing or extra inputs, syntax, consistency across
related fields, and conformance to business rules. As an example of
business rule logic, "boat" may be syntactically valid because it only
contains alphanumeric characters, but it is not valid if the input is
only expected to contain colors such as "red" or "blue."Do not rely exclusively on looking for malicious or malformed inputs
(i.e., do not rely on a blacklist). A blacklist is likely to miss at
least one undesirable input, especially if the code's environment
changes. This can give attackers enough room to bypass the intended
validation. However, blacklists can be useful for detecting potential
attacks or determining which inputs are so malformed that they should be
rejected outright.Use a whitelist of approved URLs or domains to be used for
redirection. | | | Architecture and Design | | 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. | | | Architecture and Design | Enforcement by Conversion | When the set of acceptable objects, such as filenames or URLs, is
limited or known, create a mapping from a set of fixed input values
(such as numeric IDs) to the actual filenames or URLs, and reject all
other inputs.For example, ID 1 could map to "/login.asp" and ID 2 could map to
"http://www.example.com/". Features such as the ESAPI AccessReferenceMap
[R.601.4] provide this capability. | | | Architecture and Design | | Ensure that no externally-supplied requests are honored by requiring
that all redirect requests include a unique nonce generated by the
application [R.601.1]. Be sure that the nonce is not predictable
(CWE-330). | | Note that this can be bypassed using XSS (CWE-79). | Architecture and DesignImplementation | Identify and Reduce Attack Surface | Understand all the potential areas where untrusted inputs can enter
your software: parameters or arguments, cookies, anything read from the
network, environment variables, reverse DNS lookups, query results,
request headers, URL components, e-mail, files, filenames, databases,
and any external systems that provide data to the application. Remember
that such inputs may be obtained indirectly through API calls.Many open redirect problems occur because the programmer assumed that
certain inputs could not be modified, such as cookies and hidden form
fields. | | | Operation | Firewall | 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. | Moderate | 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. |
Relationships Related CWE | Type | View | Chain |
---|
CWE-601 ChildOf CWE-896 | Category | CWE-888 | |
Demonstrative Examples (Details) - The following code is a Java servlet that will receive a GET request
with a url parameter in the request to redirect the browser to the address
specified in the url parameter. The servlet will retrieve the url parameter
value from the request and send a response to redirect the browser to the
url address.
- The following code obtains a URL from the query string and then
redirects the user to that URL.
Observed Examples - 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.
For more examples, refer to CVE relations in the bottom box. White Box Definitions None Black Box Definitions None Taxynomy Mappings Taxynomy | Id | Name | Fit |
---|
Anonymous Tool Vendor (under NDA) | | | | WASC | 38 | URl Redirector Abuse | |
References: - Craig A. Shue Andrew J. Kalafut Minaxi Gupta .Exploitable Redirects on the Web: Identification, Prevalence,
and Defense.
- Russ McRee .Open redirect vulnerabilities: definition and
prevention Issue 17. (IN)SECURE. Section:'Page 43'. Published on July 2008.
- Jason Lam .Top 25 Series - Rank 23 - Open Redirect. SANS Software Security Institute. 2010-03-25.
- OWASP .OWASP Enterprise Security API (ESAPI) Project.
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