Log4Shell scanner for Burp Suite

Detailed description can be found in our blog post about this plugin, you can also ▶️ watch a recorded demonstration video.

Note about detection capabilities: this plugin will only supply the built-in active scanner with payloads, thus for optimal coverage vs. performance, you'll have to configure your scan properly – just as with any other built-in or extension-provided scan. See #3 for detailed explanation regarding this matter.

Comparison

Feature	Log4Shell scanner (this one)	ActiveScan++ (b485a07)
Synchronous detection	✔️	✔️
Asynchronous detection	✔️	❌
Hostname detection	✔️	❌
Username detection	✔️	❌
Ability for single-issue scan (see below)	✔️	❌

Single-issue scan

If you'd like to scan only for Log4j (and not other things such as XSS or SQLi), this plugin makes it possible.

By following any of the instruction sets below, the the scanner will only perform Log4Shell checks on all insertion points if the scan configuration created as a result is used.

The easiest way

Thanks to Hannah at PortSwigger for bringing this to our attention.

1. When creating a new scan, click Select from library on the Scan configuration tab
2. Pick Audit checks - extensions only which is built into Burp Suite Pro 2.x
3. Disable every other extension (if applicable) that have an active scan check registered (such as ActiveScan++, Backslash powered scanning, Burp Bounty, etc.) so that only the Log4Shell scanner runs

The easy way

This is the version that's demonstrated in the above linked video.

1. Save extensions-only.json to your machine
2. From the leftmost Burp menu, select Configuration library
3. Click Import on the right side of the window
4. Select the location where you save the file in step 1.
5. When creating a new scan, click Select from library on the Scan configuration tab
6. Disable every other extension (if applicable) that have an active scan check registered (such as ActiveScan++, Backslash powered scanning, Burp Bounty, etc.) so that only the Log4Shell scanner runs

The manual way

This one used to be harder, but @alright21 made it much easier.

1. Create a new Scan Configuration
2. Expand Issues Reported
3. Click on one of the issues to move the focus to that list
4. Press Ctrl + A
5. Right click on the list and click on Enabled, this will disable all issues
6. Manually check the box at the last one called Extension generated issue to enabled that
7. Disable every other extension (if applicable) that have an active scan check registered (such as ActiveScan++, Backslash powered scanning, Burp Bounty, etc.) so that only the Log4Shell scanner runs

Building

Execute ./gradlew build and you'll have the plugin ready in build/libs/burp-log4shell.jar

License

The whole project is available under the GNU General Public License v3.0, see LICENSE.md.