We are investigating alerts of this DNS signature for x1.c.lencr.org.
I'd expect that a match for a clear text string in a DNS Request that it is very unlikely this is a false detection.
However to get alerts so quickly after this signature creation, suggests we are either very unlucky or a very common public internet resource if causing this fly-by access. Anyone else receiving this threat alert shortly after an apparent WF update.
This is a false positive. Palo Alto support provided the following:
I understand you are looking for a reason why this URL was marked as malware and why it flipped back. This domain is not malware, it was accidentally released last night, and as soon as we realized it was flip to shareware and disabled it. We are in the process of taking steps, such as adding this and some subdomains under lencr.org found in our database in a restrictive white list, domains under that list can't be released to malware. That step will avoid the similar FP case is caused in future.
Showing up as a PA threat for the DNS query or for the URL on a block list? The original thread was for a DNS lookup threat of supposed malware. In our logs we were getting DNS threat hits and blocks from approximately 6/11 16:30 GMT until 6/15 7:45 GMT. We have not had any threat alerts since, though we continue to see intermittent traffic to the destination.
The x1.c.lencr.org DNS/URL is not a threat itself (that I have been able to find). It is a valid Lets Encrypt domain and returns a certificate revocation list when queried. In our case we tracked it down to a component of Sophos making the queries (doing HTTP GET for the root doc with a modifier: if changed since Sep 4 2020, it hasn't been so a 304 Not Modified was returned). It appears that suspected malware may have also been querying the URL (probably for a Lets Encrypt cert generated for the malware) and the entire domain was erroneously included as a threat.
This is a benign Let's encrypt domain. The URL categorization has been cleared.
There was an issue that was resolved in 9.0.10-h2, 9.1.6, and 10.0.2, that caused URL's previously in a malicious category to get 'stuck' in that malicious category in the Firewall's DP Cache. See https://knowledgebase.paloaltonetworks.com/KCSArticleDetail?id=kA14u000000HCgjCAG
If you are running a PAN-OS version that is higher than the ones mentioned above, and you see the URL categorization stuck in a malicious category, even after it being cleared out to be Benign (verifiable in Test-A-Site), please open a Support case to have the issue investigated for root cause.
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