CVE-2013-3896
Microsoft Silverlight Information Disclosure Vulnerability
Description
CVE-2013-3896 is an information disclosure vulnerability in Microsoft Silverlight caused by improper pointer validation during access to Silverlight elements. A remote attacker can exploit this flaw through a crafted Silverlight application to obtain sensitive information from the affected system. The vulnerability allows attackers to read memory contents that should not be accessible, potentially revealing sensitive data or information useful for further exploitation. CISA has confirmed active exploitation by including CVE-2013-3896 in the Known Exploited Vulnerabilities catalog. With an EPSS percentile of 99.2%, this vulnerability is among the most frequently targeted in the entire CVE database. The affected product has reached end of life.
KEV Information
CVSS Score
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:NOpen in CalculatorAffected Products
| Vendor | Product | Version |
|---|---|---|
| microsoft | silverlight | >= 5.0, < 5.1.20913.0 |
Multiple CVSS Assessments
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
References
- http://www.us-cert.gov/ncas/alerts/TA13-288A(Third Party Advisory, US Government Resource)
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-087(Patch, Vendor Advisory)
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19003(Broken Link)
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A19055(Broken Link)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3896(US Government Resource)
Weakness Type
Since no specific CWE has been assigned to CVE-2013-3896, the underlying weakness type remains formally unspecified. The vulnerability involves improper pointer validation in the Silverlight runtime that allows out-of-bounds memory reads during element processing. This class of weakness typically enables information disclosure by allowing an attacker to access memory regions outside the intended boundaries of an object or data structure.
Impact Analysis
CVE-2013-3896 enables remote attackers to obtain sensitive information from systems running Microsoft Silverlight by exploiting improper pointer validation. The vulnerability is exploitable over the network when a user visits a web page hosting a crafted Silverlight application, requiring user interaction in the form of navigating to the malicious content. The disclosed information could include memory contents such as cryptographic keys, session tokens, user credentials stored in process memory, or internal data structures that reveal the memory layout of the application. Knowledge of memory layout is particularly valuable as it can be used to bypass Address Space Layout Randomization (ASLR) and enable exploitation of additional vulnerabilities. The EPSS percentile of 99.2% reflects the high frequency of exploitation, and the vulnerability's placement in the CISA KEV catalog confirms sustained real-world attack activity.
Exploit Maturity
CISA has confirmed active exploitation of CVE-2013-3896 by including it in the Known Exploited Vulnerabilities catalog with a remediation deadline of June 15, 2022. The EPSS percentile of 99.2% places this vulnerability among the top 1% most exploited CVEs. Information disclosure vulnerabilities in browser plugins like Silverlight are commonly chained with other exploits, where the disclosed memory information is used to defeat ASLR and enable reliable code execution through separate memory corruption vulnerabilities. The end-of-life status of Silverlight means no further patches will be released.
Remediation
- Remove Microsoft Silverlight from all systems. CISA's required action states: "The impacted product is end-of-life and should be disconnected if still in use." Since Silverlight has been discontinued, removal is the only effective remediation.
- Block Silverlight plugin execution in all web browsers through browser settings or group policy, ensuring that even if Silverlight remains installed, it cannot be invoked by web content.
- Deploy web content filtering to block web pages known to host crafted Silverlight applications targeting this vulnerability.
- Audit all systems for remaining Silverlight installations and prioritize their removal, particularly on systems that access external web content.
- Migrate any applications or workflows that still depend on Silverlight to modern web technologies such as HTML5, as Silverlight provides no ongoing security support.
Technical Details
CVE-2013-3896 exploits a flaw in how Microsoft Silverlight validates pointers when accessing Silverlight elements within a running application. During the processing of certain element types, the Silverlight runtime fails to properly validate pointer values, allowing an attacker to craft a Silverlight application that triggers out-of-bounds memory reads. These reads return data from memory regions adjacent to or outside the intended data structures, disclosing sensitive information to the attacker. The attack is delivered through a web page that loads the crafted Silverlight application, which executes in the browser plugin context. The information leak can reveal process memory contents including heap data, stack values, and internal runtime state, providing attackers with critical information for constructing reliable exploits against additional vulnerabilities such as memory corruption or code execution flaws.
Frequently Asked Questions
Is CVE-2013-3896 being actively exploited?
Yes, CISA has confirmed active exploitation of CVE-2013-3896 and added it to the Known Exploited Vulnerabilities (KEV) catalog. The EPSS percentile of 99.2% places it among the most exploited CVEs. The vulnerability is commonly used in attack chains where information disclosure enables further exploitation.
What products are affected by CVE-2013-3896?
CVE-2013-3896 affects Microsoft Silverlight. The product has reached end of life and no longer receives security updates. Any system with Silverlight still installed is vulnerable, and no patch will be released to address this issue permanently.
How do I fix CVE-2013-3896?
Since Microsoft Silverlight has reached end of life, the only effective remediation is to completely remove Silverlight from all systems. Block Silverlight plugin execution in browsers and migrate any dependent applications to modern web technologies like HTML5.
How severe is CVE-2013-3896?
CVE-2013-3896 is an information disclosure vulnerability with an EPSS percentile of 99.2%, making it one of the most actively exploited CVEs. While it does not directly enable code execution, the disclosed memory information is frequently used to bypass ASLR and enable reliable exploitation of other vulnerabilities, making it a critical component of multi-stage attacks.
Need Help With Vulnerability Management?
Our security experts can help you prioritize and remediate vulnerabilities effectively.