CVE-2015-1648 in .NET Framework
Summary
by MITRE
ASP.NET in Microsoft .NET Framework 1.1 SP1, 2.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2, when the customErrors configuration is disabled, allows remote attackers to obtain sensitive configuration-file information via a crafted request, aka "ASP.NET Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 11/30/2024
This vulnerability represents a critical information disclosure flaw in Microsoft's ASP.NET framework that affects multiple versions from .NET Framework 1.1 through 4.5.2. The vulnerability stems from improper handling of error responses when the customErrors configuration is set to disabled or off, creating an avenue for remote attackers to extract sensitive configuration data from affected systems. The flaw operates by manipulating crafted HTTP requests to trigger error responses that inadvertently reveal internal system information including configuration settings, file paths, and potentially other sensitive data that should remain hidden from external access. This issue falls under the category of CWE-200, which specifically addresses improper information exposure, making it a direct descendant of weak security controls in error handling mechanisms.
The technical exploitation of this vulnerability occurs when an attacker sends a specially crafted request to an ASP.NET application where customErrors is disabled in the web.config file. When this configuration is set to false or off, the framework's default error handling behavior becomes vulnerable to information disclosure attacks. The vulnerability is particularly dangerous because it allows attackers to gather detailed information about the application's internal structure, including database connection strings, file system paths, and other configuration parameters that could be used for subsequent attacks. This type of attack aligns with ATT&CK technique T1212, which focuses on exploitation of information disclosure vulnerabilities to gather system information for further compromise.
The operational impact of CVE-2015-1648 extends beyond simple information gathering, as the leaked configuration data can provide attackers with critical insights for launching more sophisticated attacks against the affected systems. When customErrors is disabled, applications become vulnerable to attacks that can expose sensitive configuration information including connection strings, encryption keys, and other credentials that are typically protected within the application's configuration files. This vulnerability particularly affects organizations running legacy ASP.NET applications where security configurations may not have been properly updated, creating persistent exposure windows that can be exploited by threat actors. The widespread nature of affected .NET Framework versions means that many enterprise applications remain vulnerable across different organizational environments.
Mitigation strategies for this vulnerability should focus on proper configuration management and security hardening practices. The primary recommendation is to enable customErrors in web.config files by setting the customErrors mode to "On" or "RemoteOnly" rather than "Off" or "False". This simple configuration change can effectively prevent the information disclosure behavior that enables the vulnerability. Organizations should also implement proper error handling mechanisms that do not expose internal system details to end users or external attackers. Additionally, regular security assessments and configuration reviews should be conducted to ensure that customErrors settings are properly configured across all ASP.NET applications. The vulnerability also highlights the importance of following security best practices such as those outlined in the OWASP Top Ten, particularly in relation to proper error handling and information disclosure prevention. System administrators should also consider implementing network-level protections such as web application firewalls and intrusion detection systems to monitor for suspicious request patterns that may indicate exploitation attempts.