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             AUSCERT External Security Bulletin Redistribution

                BIG-IP ASM JSON websocket security exposure
                             15 November 2019


        AusCERT Security Bulletin Summary

Product:           F5 BIG-IP products
Publisher:         F5 Networks
Operating System:  Network Appliance
Impact/Access:     Reduced Security -- Remote/Unauthenticated
Resolution:        Patch/Upgrade

Original Bulletin: 

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K70312000:BIG-IP ASM JSON websocket security exposure

Security Advisory

Original Publication Date: 15 Nov, 2019

Security Advisory Description

The BIG-IP ASM system may fail to block bad JSON websocket requests.

This issue occurs when all of the following conditions are met:

  o In the JSON profile of the affected security policy, the Parse Parameters
    setting is enabled.

    Note: This setting is enabled by default.

  o The offending request is sent as a JSON payload in a websocket connection.


The BIG-IP ASM system fails to detect the bad request and forwards it to the
backend server.


As a result of this issue, you may encounter the following symptom:

  o The backend server receives a bad JSON websocket request when the BIG-IP
    ASM system should have blocked it.

Security Advisory Status

F5 Product Development has assigned ID 763001 to this issue. F5 has confirmed
that this issue exists in the products listed in the Applies to (see versions)
box, located in the upper-right corner of this article. For information about
releases, point releases, or hotfixes that resolve this issue, refer to the
following table.

|Type of fix       |Fixes introduced |Related articles                        |
|                  |in               |                                        |
|                  |15.0.0           |K2200: Most recent versions of F5       |
|Release           |14.1.2           |software                                |
|                  |13.1.3           |                                        |
|Point release/    |         |K9502: BIG-IP hotfix and point release  |
|hotfix            |         |matrix                                  |

Security Advisory Recommended Actions


To work around this issue, you can disable the Parse Parameters setting in the
JSON profile of the affected security policy. To do so, perform the following

Impact of workaround: When you disable the Parse Parameters setting, the system
stops parsing parameters extracted from the JSON payload. In some application
environments, this may affect non-websocket traffic.

 1. Log in to the Configuration utility.
 2. Go to Security > Application Security > Content Profiles > JSON Profiles.
 3. Select the affected JSON profile.
 4. For Parse Parameters, clear the Enabled check box.
 5. Select Update.

Supplemental Information

o K51812227: Understanding Security Advisory versioning
  o K41942608: Overview of AskF5 Security Advisory articles
  o K4602: Overview of the F5 security vulnerability response policy
  o K4918: Overview of the F5 critical issue hotfix policy
  o K9502: BIG-IP hotfix and point release matrix
  o K13123: Managing BIG-IP product hotfixes (11.x - 15.x)
  o K167: Downloading software and firmware from F5
  o K9970: Subscribing to email notifications regarding F5 products
  o K9957: Creating a custom RSS feed to view new and updated documents

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