CWE-942: Permissive Cross-domain Security Policy with… | Glexia
CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains) weakness overview with consequences, detection methods, mitigations, related CVEs and…
Glexia's Take · Automated analysis
CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains
Permissive Cross-domain Security Policy with Untrusted Domains represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Executive Impact
- Confidentiality,Integrity,Availability,Access Control: Execute Unauthorized Code or Commands,Bypass Protection Mechanism,Read Application Data,Varies by Context: With an overly permissive policy file, an attacker may be able to bypass the web browser's same-origin policy and conduct many of the same attacks seen in Cross-Site Scripting (CWE-79). An attacker can exploit the weakness to transfer private information from the victim's machine to the attacker, manipulate or steal cookies that may include session information, create malicious requests to a web site on behalf of the victim, or execute malicious code on the end user systems. Other damaging attacks include the disclosure of end user files, installation of Trojan horse programs, redirecting the user to some other page or site, running ActiveX controls (under Microsoft Internet Explorer) from sites that a user perceives as trustworthy, and modifying presentation of content.
Developer Pattern
CWE-942 is the kind of defect developers can usually prevent with explicit validation, safer framework defaults, and tests that exercise hostile input or unsafe state transitions.
Automation confidence
high confidence from CWE-942, 4.20.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Official CWE Definition
CWE-942: Permissive Cross-domain Security Policy with Untrusted Domains
The product uses a web-client protection mechanism such as a Content Security Policy (CSP) or cross-domain policy file, but the policy includes untrusted domains with which the web client is allowed to communicate.
Developer And Remediation Guidance
How teams prevent and detect this weakness
Causes
- These cross-domain policy files mean to allow Flash and Silverlight applications hosted on other domains to access its data: Flash crossdomain.xml :,Silverlight clientaccesspolicy.xml :,These entries are far too permissive, allowing any Flash or Silverlight application to send requests. A malicious application hosted on any other web site will be able to send requests on behalf of any user tricked into executing it.
Remediation
- Architecture and Design,Operation: Define a restrictive Content Security Policy [REF-1486] or cross-domain policy file.
- Architecture and Design,Operation: Avoid using wildcards in the CSP / cross-domain policy file. Any domain matching the wildcard expression will be implicitly trusted, and can perform two-way interaction with the target server.
- Architecture and Design,Operation: For Flash, modify crossdomain.xml to use meta-policy options such as 'master-only' or 'none' to reduce the possibility of an attacker planting extraneous cross-domain policy files on a server.
Detection
- Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Mappings
Related CVEs, CWEs, and ATT&CK context
Related CWEs
ATT&CK Relevance
ATT&CK relevance is shown only when reviewed or responsibly inferred.