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Database

Config Files Missing Suppress Vuln Header

Description

Detects if the X-Powered-By header is not properly suppressed in .NET configuration files. This header reveals information about the web server technology stack which could help attackers identify version-specific vulnerabilities.

Weakness:

037 - Technical information leak

Category: Information Collection

Detection Strategy

    • Search for <customHeaders> sections in .NET configuration files

    • Check if there is a <remove> tag with name="X-Powered-By" within the customHeaders section

    • Report a vulnerability if customHeaders exists but does not contain the proper header removal configuration

Vulnerable code example

<!-- web.config -->
<configuration>
    <system.webServer>
        <httpProtocol>
            <customHeaders> <!-- Vulnerable: Missing important security headers like X-Frame-Options -->
            </customHeaders>
        </httpProtocol>
    </system.webServer>...

✅ Secure code example

<!-- web.config -->
<configuration>
    <system.webServer>
        <httpProtocol>
            <customHeaders>
                <remove name="X-Powered-By"/> <!-- Remove server info disclosure -->
                <add name="X-Frame-Options" value="SAMEORIGIN"/> <!-- Prevent clickjacking -->
                <add name="X-Content-Type-Options" value="nosniff"/> <!-- Prevent MIME type sniffing -->...