nowafpls – Burp Plugin to Bypass WAFs through the insertion of Junk Data

June 21, 20243 min read

Most web application firewalls (WAFs) have limitations for how much data they can process when a request body is sent. This means for HTTP requests that contain a request body (i.e. POST, PUT, PATCH etc), it is usually possible to bypass the WAF by simply prepending junk data.

When the request is padded with this junk data, the WAF will process up to X kb of the request and analyze it, but everything after the limits of the WAF will pass straight through.

nowafpls is a simple Burp plugin which will contextually insert this junk data into your HTTP request inside the repeater tab. You can select from a preset amount of junk data you want inserted, or you can insert an arbitrary amount of junk data by selecting the “Custom” option.

This tool is just 80 or so lines of Python, it’s incredibly simple but works for most WAFs lol.

Documented WAF Limitations

WAF ProviderMaximum Request Body Inspection Size Limit
Cloudflare128 KB for ruleset engine, up to 500 MB for enterprise
AWS WAF8 KB – 64 KB (configurable depending on service)
Akamai8 KB – 128 KB
Azure WAF128 KB
Fortiweb by Fortinet100 MB
Barracuda WAF64 KB
Sucuri10 MB
Radware AppWallup to 1 GB for cloud WAF
F5 BIG-IP WAAP20 MB (configurable)
Palo Alto10 MB
Cloud Armor by Google8 KB (can be increased to 128 KB)

Installing nowafpls

nowafpls is a Jython based Burp Plugin.

  1. Clone or download this repo.
  2. Go to the extensions tab in Burp Suite.
  3. Click “Add”
  4. Select Extension Type – Python
  5. Select “nowafpls.py” that you downloaded in Step 1

Using nowafpls


  1. Send any request to the repeater tab that you’d like to bypass WAF for.
  2. Put your cursor in a place you would like to insert junk data.
  3. Right click -> Extensions -> nowafpls
  4. Select how much junk data you want to insert
  5. Click “OK”

nowafpls will insert junk data as per the type of request (URLEncoded/XML/JSON) automatically.

Caido Version

The Caido version of this plugin is maintained by @Rhynorater and can be found at the below gist:


or in the EvenBetter Workflow Library.


  • Shubham ShahInitial workgithub



Direct View On Github

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