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[R1] Palo Alto Networks PAN-OS /api Multiple Parameter Handling Remote DoS

Medium

Synopsis

While developing a plugin to detect PAN-SA-2016-0005, Tenable discovered a different vulnerability in the panUserLogin() function within panmodule.so that could result in an unauthenticated remote DoS. The PAN-OS function calls the glibc strcpy_chk() function to copy a user-supplied username and password to a buffer. If the 'username' parameter exceeds 0x100 bytes or the 'password' parameter exceeds 0x80 bytes, strcpy_chk() causes the process to terminate. When the process terminates, it is re-spawned by its parent process, so it may not be obvious that process had died and may be a partial DoS scenario like previous. However, the log will show it had:

2016-03-19 01:21:34.256 -0400 INFO: appweb: exited, Core: True, Exit signal: SIGABRT
2016-03-19 01:21:48.875 -0400 INFO: appweb: process running with pid 6700
This has been tested on PAN-OS 7.0.1 running on a VM-series firewall.

Solution

Palo Alto has released version 7.0.8 and 7.1.0 to address this issue.

Disclosure Timeline

2016-03-21 - Issue discovered
2016-03-22 - Tried to report via Vuln Report page, received "Sorry, an error occurred while processing your request."
2016-03-22 - Tweeted to @PaloAltoNtwks, emailed [email protected] notifying
2016-03-24 - Sent another email asking about broken form
2016-03-27 - Form still broken
2016-04-01 - Form still broken, another tweet sent to @PaloAltoNtwks
2016-04-03 - Two PaloAlto employees reach out after Tweet to help establish contact
2016-04-03 - Report sent directly to Global Security Response Team member
2016-04-03 - PaloAlto GSRT confirms receipt of report
2016-04-04 - Vendor indicates it was found internally, fixed in 7.1.0 released today. Asks if we can confirm.
2016-04-04 - Tenable does not have an active license to get 7.1.0 currently, notifies vendor.
2016-05-17 - Tenable informs vendor, still no access to 7.1.0, asks how to proceed.
2016-05-18 - Vendor says checking with engineering on other supported releases being affected.
2016-05-18 - Tenable researcher got hands on 7.1.0 after all, confirms not vulnerable.
2016-05-20 - Vendor says working on backport to 7.0.8, and evaluating other products affected
2016-05-23 - Vendor confirms only impacted 7.0. PAN-OS 7.0.8 scheduled for June 13th.
2016-06-21 - Vendor releases PAN-OS 7.0.8.
2016-06-27 - Vendor releases formal advisory for the issue.

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