Detect and sanitize HAR files with Data Loss Prevention

HTTP Archive (HAR) files are used by engineering and support teams to capture and share web traffic logs for troubleshooting. However, these files routinely contain highly sensitive data — including session cookies, authorization headers, and other credentials — that can pose a significant risk if uploaded to third-party services without being reviewed or cleaned first.

Gateway now includes a predefined DLP profile called Unsanitized HAR that detects HAR files in HTTP traffic. You can use this profile in a Gateway HTTP policy to either block HAR file uploads entirely or redirect users to a sanitization tool before allowing the upload to proceed.

How to configure a HAR file policy

In the Cloudflare dashboard ↗, go to Zero Trust > Traffic policies > Firewall Policies > HTTP and create a new HTTP policy using the DLP Profile selector:

Selector	Operator	Value	Action
DLP Profile	in	Unsanitized HAR

Then choose one of the following actions:

• Block: Prevents the upload of any HAR file that has not been sanitized by Cloudflare's sanitizer. Use this for strict environments where HAR file sharing must be disallowed entirely.
• Block with Gateway Redirect: Intercepts the upload and redirects the user to https://har-sanitizer.pages.dev/, where they can sanitize the file. Once sanitized, the user can re-upload the clean file and proceed with their workflow.

Sanitized HAR recognition

HAR files processed by the Cloudflare HAR sanitizer receive a tamper-evident sanitized marker. DLP recognizes this marker and will not re-trigger the policy on a file that has already been sanitized and has not been modified since. If a previously sanitized file is edited, it will be treated as unsanitized and flagged again.

Visibility in Gateway logs

Gateway logs will reflect whether a detected HAR file was classified as Unsanitized or Sanitized, giving your security team full visibility into HAR file activity across your organization.

For more information, refer to predefined DLP profiles.