Thread-Log: Virus found

[w.naderer]

Hello,
under our Threat-Log I found some Virus entries. The Attacker is an own PC from another vlan. We want to install windows updates over Ivanti-Patchmanagement with the original windows update service. And now the maschine, which we will patch, will do a virus attack - msiexec.exe and wscript.exe. Palo ID 194147259, Application ms-ds-smbv2...
We scanned both machines with a lot of tools and virus-scanner = nothing found!!!
Can somebody tell me the location of the infected files, which will shown in the thread log?
Have you some Tips for me?
Thank you verry much.

Cu
Wolfgang

[tcasw86]

To confirm this is on the firewall threat log? What was the action taken? If it droped or reset the session then traffic wouldn't have made it through to the host as it was blocked by the firewall.

[mivaldi]

I found that multiple Palo Alto Networks customers have reported this issue.

After investigation, I've concluded these are caused by signature collisions with a signature for malicious sample 7e3bdff41913aadc0f5e1e0cf65a9197a060ad68bd9196d92ee240e0ab702085.

I've submitted a request to fine tune the associated signature, so that it is less likely to produce signature collisions.

The issue should be resolved by Monday COB.

[w.naderer]

Hi,
thanks for your responses 🙂
Did we talk about the same story?! How can I ensure that this virus message is a hoax or not?
At the top some Images about my virus troubles

How can I determine the directory of the affected file?

Thank you

Kind regards

Wolfgang

[mivaldi]

Wolfgang,

Please upgrade to the latest Antivirus package and do let me know if you still see the signature triggering.

I tried to resolved this issue, but the msiexec.exe sample I had to work with was not triggering the signature collision any longer.

If yours continues to trigger after updating Antivirus, please locate the msiexec.exe file that triggers the signature, and share its sha256 hash with me.

[w.naderer]

Hi Mivaldi,

Take a look on my uploaded image, please.
I don't unterstand this....

For Explanation:
On the Victim Machine we scan the attacker with a patchmanagement software. No login on the attacker machine!
Why does the palo shows urls unter the file name?! We also scanned the victim machine with different anti virus software as TrendMicro and Kaspersky - nothing found!

I hope you have any ideas?

Thank you 🙂

cu
Wolfgang

[mivaldi]

The URL's in the file names looks like a product defect. If I remember correctly, it is caused by limitations with the SMB decoder, which by the way has been significantly improved in PAN-OS 8.1. I would focus my attention on resolving the collision though. Have you been able to spot the msiexec.exe file causing the signature to trigger? 

[w.naderer]

Hello Mivaldi,

I have uploaded the msiexe.exe and wscript.exe...

https://we.tl/J6oxaWfDZ0

Thank you

cu

Wolfgang

[mivaldi · Accepted solution]

Thank you for the samples. The issue is resolved and the signatures will be removed from tomorrow's release of Antivirus. In the future please report these type of issues by opening a case with Support.

[w.naderer]

Hello Mivaldi,
Thank you for your Support.
Can I assume that this was really a virus false report?
I will test the problem after Antivirus update oh the firewall and give you a Feedback!

Thanks 🙂

cu

Wolfgang

[mivaldi]

Wolfgang,

 They weren't false positives. False positives are when WildFire gives a Benign file a Malicious verdict.

 In this case, WildFire gave the files a Benign verdict, but they were triggering Antivirus signatures. We call these Signature Collisions. These happen when the digital patterns that the firewall looks at to identify a file, concide between a Benign sample and an Antivirus signature that has been generated from a Malicious sample that is similar in structure to the Benign file.

 You can read more about these at:

https://live.paloaltonetworks.com/t5/Threat-Vulnerability-Articles/What-is-a-signature-collision/ta-...

[w.naderer]

Hi Mivaldi,

Your Changes was successfully 🙂

But can you check also this file: https://we.tl/cu2QR8Uxh2

I think, it's the same...

Thank you very much!

cu

Wolfgang

[w.naderer]

Hello Mivaldi,

I need your help once again...

Thank you

cu

Wolfgang

[mivaldi]

It was a virus false report caused by a Signature Collision.

https://live.paloaltonetworks.com/t5/Threat-Vulnerability-Articles/What-is-a-signature-collision/ta-...

[mivaldi]

Wolfgang, for the new sample please open a case with support.