ms-ds-smbv3 - Trojan-Downloader/Win32.guloader.ao

[Matthew_Hayes]

We are receiving a large quantity of logs affecting a limited number of users for this threat

IDName: Trojan-Downloader/Win32.guloader.ao

Unique Threat ID: 479496371

Create Time: 2022-04-05 09:11:48 (UTC)

Threat ID: 2837943

Current Release: 4338 (2023-01-23 UTC)

First Release: 4044 (2022-04-05 UTC)

We suspect that this is a false positive, Is anyone experiencing the same Issue or have any ideas on weather this can be resolved? 

Thanks.

[ymiyashita]

I would suggest to find the sample which is being blocked by the signature and check the verdict (you can upload it to the WildFire cloud to see the verdict). If it's benign, you can set an exception to allow the file temporarily as needed. It is called 'signature collision'.

The signature was created for a bunch of malware samples. We should keep the signature enabled instead of disabling it.
https://threatvault.paloaltonetworks.com/?query=479496371&type=

References:
- Manually Upload Files to the WildFire Portal
https://docs.paloaltonetworks.com/wildfire/9-1/wildfire-admin/submit-files-for-wildfire-analysis/man...

- What is an Antivirus collision in the case of a False Positive, and how can we deal with it?
https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClWICA0

- How to Use Anti-Spyware, Vulnerability and Antivirus Exceptions to Block or Allow Threats
https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000ClcrCAC

[Matthew_Hayes]

Thanks for replying! 

The issue we are facing is that in the Logs we are seeing it does not supply a file Hash or any other indication to which files are actively causing these alerts to occur, It only shows the application as MS-DS-SMBv3 which does not really sound correct. 

I will look into the AV collision to check if this is applicable.

Thanks, Matt.

[ymiyashita · Accepted solution]

You may also want to look at the WildFire submission log. If the WildFire analysis profile is already enabled, you can find the corresponding log with the file hash and its verdict.
By the way, as the file was transferred over SMBv3, the filename might be incorrect.

Reference:
What to do when file information is blank and using SMBv3
https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA10g000000boOXCAY

[Matthew_Hayes]

Thanks @ymiyashita, After checking that last link you posted it explains why a lot of the information within the logs is missing and why it would be picked up as a virus within the firewall. 

There were no wildfire submissions related to the threat logs either so I suspect that a false positive is the case

Thanks again, Matt

[MarjorieJohnson]

Thanks for the solution, you made my day 🙂

[JohnHarris]

Thanks for the link, you made my day.