CWE-538: Insertion of Sensitive Information into Externally-Accessible File or Directory

What is Insertion of Sensitive Information into Externally-Accessible File or Directory?

• Overview: This vulnerability occurs when sensitive information is stored in files or directories that are accessible to users who should not have access to the sensitive information itself. This can lead to unintended data exposure.

• Exploitation Methods:

• Attackers can exploit this vulnerability by gaining access to files or directories that contain sensitive information due to insufficient access controls.
• Common attack patterns include browsing directories, reading files via unintended access, and exploiting misconfigured permissions.

• Security Impact:

• Direct consequences include unauthorized access to sensitive information such as credentials, personal data, or proprietary information.
• Potential cascading effects include further compromise of systems, privilege escalation, and data leaks.
• Business impact may involve reputational damage, financial loss, and legal liabilities due to breaches of privacy and data protection regulations.

• Prevention Guidelines:

• Specific code-level fixes include ensuring that sensitive information is not stored in publicly accessible directories and using encryption for data at rest.
• Security best practices involve implementing strict access controls, regularly auditing files and directories for sensitive information, and employing the principle of least privilege.
• Recommended tools and frameworks include using file system monitoring and data loss prevention (DLP) solutions to detect and prevent unauthorized access to sensitive files.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not specified

Vulnerable Code Example

// Vulnerable code: Sensitive information such as database credentials are written to a file
// that could be externally accessible.

const fs = require('fs');

// Sensitive database credentials
const dbConfig = {
    user: 'admin',
    password: 'secretpassword'
};

// Write configuration to a file
fs.writeFileSync('public/config.json', JSON.stringify(dbConfig));  // {15}
// The config file is saved in a publicly accessible directory, making it vulnerable to unauthorized access.

How to fix Insertion of Sensitive Information into Externally-Accessible File or Directory?

To resolve this issue, follow these steps:

1. Avoid Storing Sensitive Data in Public Directories: Never store sensitive data in directories that are publicly accessible.
2. Use Environment Variables: Store configuration data in environment variables instead of in files.
3. Secure File Permissions: Ensure that sensitive files are stored in directories with strict access permissions.
4. Encrypt Sensitive Information: If sensitive information must be stored, consider encrypting it.

Fixed Code Example

const fs = require('fs');

// Retrieve database credentials from environment variables
const dbConfig = {
    user: process.env.DB_USER,  // {14}
    password: process.env.DB_PASSWORD  // {15}
};

// Ensure that sensitive data is never written to a publicly accessible file
// If configuration needs to be saved, ensure the file is in a secure location
// For demonstration, the sensitive part is stored securely
const secureConfig = {
    user: dbConfig.user,
    // Do not store the password in any file
};

// Save non-sensitive configuration to a more secure location
fs.writeFileSync('/secure/config.json', JSON.stringify(secureConfig));  // {18}
// Ensure the '/secure' directory has appropriate permissions to restrict access.

By adopting these practices, you can prevent the accidental exposure of sensitive information and enhance the security of your application.