SANS Stormcast Monday, August 4th, 2025: Legacy Protocols; Sonicwall SSL VPN Possible 0-Day;

SANS Internet Stormcenter Daily Cyber Security Podcast (Stormcast)

Scans for pop3user with guessable password
A particular IP assigned to a network that calls itself Unmanaged has been scanning telnet/ssh for a user called pop3user with passwords pop3user or 123456 . I assume they are looking for legacy systems that either currently run pop3 or ran pop3 in the past, and left the user enabled.
https://isc.sans.edu/diary/Legacy%20May%20Kill/32166
Possible Sonicwall SSL VPN 0-Day
Arcticwolf observed compromised Sonicwall SSL VPN devices used by the Akira group to install ransomware. These devices were fully patched, and credentials were recently rotated.
https://arcticwolf.com/resources/blog/arctic-wolf-observes-july-2025-uptick-in-akira-ransomware-activity-targeting-sonicwall-ssl-vpn/
PAM Based Linux Backdoor
For over a year, attackers have used a PAM-based Linux backdoor that so far has gotten little attention from anti-malware vendors. PAM-based backdoors can be stealthy, and this one in particular includes various anti-forensics tricks.
https://www.nextron-systems.com/2025/08/01/plague-a-newly-discovered-pam-based-backdoor-for-linux/