Permissive Cross-domain Security Policy with Untrusted Domains

Opis

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.

If a cross-domain policy file includes domains that should not be trusted, such as when using wildcards under a high-level domain, then the application could be attacked by these untrusted domains. In many cases, the attack can be launched without the victim even being aware of it.

Skutki

• 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.

Zapobieganie

• Architecture and Design, Operation · Attack Surface Reduction

  Define a restrictive Content Security Policy [REF-1486] or cross-domain policy file.

• Architecture and Design, Operation · Attack Surface Reduction

  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 · Environment Hardening

  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.

Przykłady podatności

• CVE-2012-2292 Product has a Silverlight cross-domain policy that does not restrict access to another application, which allows remote attackers to bypass the Same Origin Policy.
• CVE-2014-2049 The default Flash Cross Domain policies in a product allows remote attackers to access user files.
• CVE-2007-6243 Chain: Adobe Flash Player does not sufficiently restrict the interpretation and usage of cross-domain policy files, which makes it easier for remote attackers to conduct cross-domain and cross-site scripting (XSS) attacks.
• CVE-2008-4822 Chain: Adobe Flash Player and earlier does not properly interpret policy files, which allows remote attackers to bypass a non-root domain policy.
• CVE-2010-3636 Chain: Adobe Flash Player does not properly handle unspecified encodings during the parsing of a cross-domain policy file, which allows remote web servers to bypass intended access restrictions via unknown vectors.

Słabość nadrzędna

• CWE-863 Incorrect Authorization
• CWE-923 Improper Restriction of Communication Channel to Intended Endpoints
• CWE-183 Permissive List of Allowed Inputs

Może prowadzić do

• CWE-668 Exposure of Resource to Wrong Sphere

Kiedy powstaje

• Implementation
• Architecture and Design — COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.

Dotyczy

Not Language-Specific, Web Based, Web Server

Źródła

1. Content Security Policy Cheat Sheet — OWASP
2. Setting a crossdomain.xml file for HTTP streaming — Apurva Udaykumar, Adobe, 2012
3. Cross-domain policy for Flash movies — Adobe, Adobe
4. HTTP Communication and Security with Silverlight — Microsoft Corporation
5. Network Security Access Restrictions in Silverlight — Microsoft Corporation
6. Analyzing the Crossdomain Policies of Flash Applications — Dongseok Jang, Aishwarya Venkataraman, G. Michael Sawka, Hovav Shacham, 2011