CVE-2014-6271 Shellshock rules blocking Sharepoint traffic?

[Khang_Than-Trong]

This morning our PAs began blocking internal Sharepoint document access with App-ID 36995. The traffic that is blocked is coming from IE11 + Windows 7 clients.

I'm not sure why this bash vulnerability is being flagged as affecting Windows servers + clients in this case. Anyone have ideas?

[vkalal · Accepted solution]

It's blocking it because of a vulnerability called an arbitrary code execution exploit. Most of these vulnerabilities allow the execution of machine code which may allow the attacker to run arbitary commands.

[vkalal]

It's also vulnerable to injection and execution of shell code

[Khang_Than-Trong]

Thanks for the reply. Any ideas how to mitigate/address this? Admittedly, I'm not sure what can be done on the client-side to allow for the traffic/access to be non-exploitable.

[vkalal]

The default action is set to Alert to allow administrators to choose their desired action.

[Khang_Than-Trong]

Thanks. Looks like it may be unpatched Office clients triggering this from my inspection/testing.

[Lucky]

Hi Khang,

Shellshock is a fancy name for specially crafted packets in client-to-server communication that are trying to exploit bash and could lead to execution of arbitrary commands on the server.

If you have your own trusted hosts on the originating side (if this is from your own network as you are suggesting) I would definitely open a case with TAC and see if this is a false positive or you might have compromised hosts in your network that are trying to enumerate / exploit servers within. If it is False Positive - PAN needs to solve it; if it is not False Positive than some probes for vulnerable bash inside of your network would be considered indicators of compromise.

Best regards,

Luciano

[Khang_Than-Trong]

Thanks for the reply. I did some testing with the Sharepoint document access traffic from patched Windows workstations and they're not triggering the PA alerts/blocking so I chalk this up to the desktops not being patched yet. 

[superture]

Hi,

What components were unpatched? Windows, IE or Office?

Have several clients alerting on this in morning. Destination is 2 sharepoint servers on the LAN and 1 residning in one-drive.

Upgraded our HA to 7.0.5h2 two days ago.

[Khang_Than-Trong]

Office components weren't updated.