In this two-part series, SpiderLabs explores the malicious traffic associated with Proton66, revealing the extent and nature of these attacks.

Mass scanning and exploit campaigns targeting multiple sectors
Starting from January 8, 2025, SpiderLabs observed an increase in mass scanning, credential brute forcing, and exploitation attempts originating from Proton66 ASN targeting organizations worldwide. Although malicious activity was seen in the past, the spike and sudden decline observed later in February 2025 were notable, and offending IP addresses were investigated.

AS198953, belonging to Proton66 OOO, consists of five net blocks, which are currently listed on blocklists such as Spamhaus due to malicious activity. Net blocks 45.135.232.0/24 and 45.140.17.0/24 were particularly active in terms of mass scanning and brute force attempts. Several of the offending IP addresses were not previously seen to be involved in malicious activity or were inactive for over two years. For instance, the last activities reported in AbuseIPDB for the IP addresses 45.134.26.8 and 45.135.232.24 were noted in November and July 2021, respectively.