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             AUSCERT External Security Bulletin Redistribution

        Session data may be exposed when using a proxy to multiplex
                   connections to the BIG-IP APM system
                              18 October 2018


        AusCERT Security Bulletin Summary

Product:           F5 BIG-IP products
Publisher:         F5 Networks
Operating System:  Network Appliance
Impact/Access:     Access Confidential Data -- Remote with User Interaction
Resolution:        Mitigation

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

K13217575:Session data may be exposed when using a proxy to multiplex 
connections to the BIG-IP APM system

Security Advisory

Original Publication Date: 18 Oct, 2018

Security Advisory Description

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

  o The BIG-IP APM system is configured to perform NTLM SSO authentication to
    back-end servers.
  o A proxy in front of the BIG-IP APM system multiplexes connections from
    different users.


Users may be exposed to session data from other user connections.


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

  o Users connecting to the BIG-IP APM system see other user's session data or
    application data.

Security Advisory Status

F5 Product Development has assigned ID 710984 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 in|Related articles|
|Release             |None               |None            |
|Point release/hotfix|None               |None            |

Security Advisory Recommended Actions


To work around this issue when using IIS servers on the back end, you can
configure the authPersistSingleRequest=TRUE metabase property on the IIS
server.  To work around this issue using an iRule, you can create an iRule
using the following code and associate it with the virtual server. To do so,
perform the following procedure:

Impact of workaround: The impact of the suggested workaround depends on the
specific environment. F5 recommends that you test any such changes during a
maintenance window and consider the possible impact to your environment.

 1. Log in to the BIG-IP Configuration utility.
 2. Navigate to Local Traffic > iRules.
 3. Click Create.
 4. Type a name in the Name field.
 5. Enter the following code in the Definition field:

    when HTTP_REQUEST {
      if { not ([HTTP::cookie exists "MRHSession"]) } {
      set sid [HTTP::cookie "MRHSession"]
      if { not ([ACCESS::session exists -state_allow -sid $sid]) } {
      set laddr [IP::local_addr]
      set lport [TCP::local_port]
      set raddr [IP::remote_addr]
      set rport [TCP::remote_port]
      set tuple_hash [sha256 "$laddr:$lport,$raddr:$rport"]
      set key "access_session.for.flow.$tuple_hash"
      set result [table add $key $sid]
      if { $result eq $sid } {
        # letting request go
      # this request requires detaching serverside flow, then re-attaching
      set selected [LB::select]
      eval $selected
      table set $key $sid

    # clean-up iRule for when the connection closes
    when CLIENT_CLOSED {
      set laddr [IP::local_addr]
      set lport [TCP::local_port]
      set raddr [IP::remote_addr]
      set rport [TCP::remote_port]
      set tuple_hash [sha256 "$laddr:$lport,$raddr:$rport"]
      set key "access_session.for.flow.$tuple_hash"
      table delete $key

 6. Click Finished.
 7. Navigate to Local Traffic > Virtual Servers.
 8. Click Edit in the Resources column for the affected virtual server.
 9. Under iRules, click Manage.
10. Click the name of the newly created iRule and click << to move it to the
    Enabled box.
11. Click Finished.

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 - 13.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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