Optionsbleed Vulnerability in Apache2: Remote Data Exposure Risk
Summary
ALPINE-CVE-2017-9798: Apache httpd allows remote attackers to read secret data from process memory if the Limit directive can be set in a user's .htaccess file, or if httpd.conf has certain misconfigurations, aka Optionsbleed. Affects apache2 versions < 2.4.27-r1. Fixed in 2.4.27-r1. How to fix ↓
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Background
Apache HTTP Server, commonly referred to as Apache2, is a widely-used open-source web server software that enables the hosting of websites and web applications. It is known for its flexibility, robust performance, and extensive feature set, including support for various protocols and modules. However, certain misconfigurations and directives, such as the Limit directive in .htaccess files, can expose sensitive data to unauthorized users, leading to significant security risks.
Vulnerability Detail
The Optionsbleed vulnerability allows remote attackers to read sensitive data from the server's process memory if the Limit directive is improperly configured in a user's .htaccess file or in the main configuration file (httpd.conf). This vulnerability affects Apache HTTP Server versions up to 2.4.27 and can be exploited by sending an unauthenticated OPTIONS HTTP request. The issue is classified as a use-after-free vulnerability, meaning that the secret data may not always be sent, and the specific data exposed can vary based on server configuration and other factors.
How To Fix
Minimum fixed version
2.4.27-r1
This is the first release that contains the fix.
sudo apk add --upgrade apache2Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can block exploitation of this vulnerability by modifying the server configuration to restrict the use of the Limit directive in .htaccess files. Additionally, review and correct any misconfigurations in your httpd.conf file that may expose sensitive data.
Conclusion
The Optionsbleed vulnerability poses a significant risk to Apache HTTP Server installations, allowing unauthorized access to sensitive data. It is crucial to update to the patched version and implement recommended security practices to safeguard your web applications.
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FAQ
Optionsbleed is a security vulnerability in Apache HTTP Server that allows attackers to read sensitive data from the server's memory through misconfigured .htaccess files.
Apache HTTP Server versions up to 2.4.27 are affected by the Optionsbleed vulnerability.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
The CVSS score for the Optionsbleed vulnerability is 7.5, indicating a high severity level.
If an immediate update is not possible, implement the recommended workarounds to restrict the Limit directive and review your server configurations to mitigate the risk.
References
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