topic Re: Threat Log False Positives in Advanced Threat Prevention Discussions

Threat Log False Positives

ShaneMcG — Thu, 14 Oct 2021 05:57:14 GMT

Hi,

In short - I'm looking to a way to identify false positives.

My organisation's anti virus profiles within our Palo NGFWs are detecting multiple generic threats of a 'medium' level and blocking them. I'm trying to determine whether any of these are false positives, and if they should remain blocked.

The threat names all follow the same format: Virus/Win32.WGeneric.######, with the last 6 digits varying for each threat. When I check the threat vault, there is no further information provided as to the nature of the threat, other than a list of hashes associated with it.

I've entered these hashes into VirusTotal.com and also AlienVault to see if any record of these as a malicious activity exists, but I've been unable to find any matches for the 30 or so hashes I've checked so far.

Does anyone know what these hashes actually are? Are they the hash of the file being transferred, or the type of threat itself? We've gone to the source device where the threat was generated and there is no record of the hash that the threat corresponds to in Palo's Threat Vault.

Re: Threat Log False Positives

OtakarKlier — Thu, 14 Oct 2021 17:07:57 GMT

Hello,

The generic ones are the hardest to prove one way or another. If possible I would suggest you send them to wildfire for analysis and hope that PAN comes out with a signature. Or you can open a case and have then do the same thing that way.

Regards,

Re: Threat Log False Positives

goku123 — Thu, 14 Oct 2021 18:17:22 GMT

Hi @ShaneMcG

When you query for an AV signature name or Signature ID in Threatvault, the sha256 hashes reported in Threatvault are the sha256 hashes of files for which this signature was generated.

e.g. If you search for the following:

Name: Virus/Win32.WGeneric.brwesg
Sig id: 438164772

Threatvault shows 318f37ae7d23f954c51f3aef2d06edaaec60e01639131f2efb801cbab7168fec as one of the sample SHA256 hashes for this signature. This sample 318f3.. was deemed to be malware in the WildFire sandbox and thus the signature shows the association as coverage for this sample.

However, if the file transfer that triggered a signature was not for one of the hashes listed or no other malware was found, as @OtakarKlier suggested, please report this via a case and a support expert can help with next steps.

Re: Threat Log False Positives

KdG-Netadmin — Wed, 26 Jan 2022 23:16:07 GMT

Hello,

We have this problem too. I already excluded more than 50 of these WGeneric virusses :(. A few times we reported the false positive to TAC through our partner, but we have to follow article https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000Cm3aCAC . It just takes too much time to collect the data, start a case, .... And this on top of the case I have with my end user. It would be a great relief if we could exclude this entire category of viruses (at least the new signatures in this category), because it triggers too much false positives.

Regards