First alert we had from rule SID 20842 was on 23 Nov at 17:39 GMT. Since then have had 230 alerts to around 50 different Windows 10 hosts, all this rule, 29 different IP source addresses, all source port 80, various destination ports.
Looking up the source IP addresses most of them look like CDN IPs, some identified as Akamai Technologies, couple I've seen Microsoft update mentioned. Looking at netstat on one host it looked like SearchApp.exe was connected to one of these sources. I checked the SearchApp.exe program certificate and it was genuine. I just can't understand why this rule is suddenly generating these alerts. If the IPs are genuine CDN sources, why they are generating alerts? I'm not aware of any network or firewall changes that could be a factor.I've logged a ticket with support, but haven't heard anything back and am desperate to understand what is going on here.
Top 10 IPS sources since first alert (all rule 20842):
Full email alert:
Intrusion Prevention Alert An intrusion has been detected. The packet has been dropped automatically. You can toggle this rule between "drop" and "alert only" in WebAdmin. Details about the intrusion alert: Message........: FILE-OTHER Interactive Data eSignal stack buffer overflow attempt Details........: https://www.snort.org/search?query=20842 Time...........: 2021-11-23 17:39:17 Packet dropped.: yes Priority.......: high Classification.: Attempted User Privilege Gain IP protocol....: 6 (TCP) Source IP address: 188.8.131.52 Source port: 80 (http) Destination IP address: 192.168.[x].[x] Destination port: 58759
Any help would be very much appreciated.
We've resolved this by deploying a GPO disabling automatic updates from the Microsoft Store. We've had no more of these IPS alerts since.