Firewall Wizards mailing list archives
Strange Traffic
From: "Mark" <firewalladmin () bellsouth net>
Date: Mon, 22 May 2006 18:24:01 -0400
Hi All: I was wondering if anyone else has run into this and know what may be causing it. Recently my IDS started to log several suspicious entries, specifically something (one or more internal machines) attempts to connect to various IP addresses from source port 25 to a random high port. Here are some specifics: 1. The internal IP addresses are legitimate addresses in the sense that they are the same as my 3 internal class C addresses, but spoofed because I know about 40-50 of the addresses they claim to be from are not currently assigned to any workstations. 2. Source IP is that of an internal address, source port is 25. 3. Destination IP is usually something in Taiwan (I've noticed about 6 addresses there, one in Korea, one in Phoenix and one in Atlanta). Many appear to be dynamically assigned. One even resolved as an ADSL IP address. Destination port is a random high port, anywhere from about 17,000 something to as high as 53,000 something. 4. The IDS is logging it as SMTP Malformed Data - Malformed Banner. 5. The events are logged about once every other day, and a total of about 50-60 are logged within about 10 minutes time, and start anywhere from 3:30 AM to 5:30 AM. This has been happening for about 2 weeks now. My firewall is blocking the outgoing traffic but I can't seem to pin down what is causing it. We run updated AV and a corporate version of Anti Spyware, neither of which are logging anything unusual. We also run a popular vulnerability scanner regularly that hasn't come up with anything unusual. Does anyone have any ideas if this is some sort of Spyware? Any ideas on tracking down the source? I'm open to any and all suggestions. Thanks for taking the time to read this. Mark _______________________________________________ firewall-wizards mailing list firewall-wizards () listserv icsalabs com https://listserv.icsalabs.com/mailman/listinfo/firewall-wizards
Current thread:
- Strange Traffic Mark (May 22)