We have Exchange Server 2007 published with isa server 2006. Recently I've noticed that Unidetified ip packets are sent from exchange server to external IPs. Isa logging shows that source port is 25 and external ports are random:
Exchange IP source port destination IP destination Port
10.0.0.83 25 59.97.56.105 4884
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there are a lot of same logs in isa logging. I've Kaspersky antivirus for file scanning and forefront for exchange. I think that my system is infected, but antivirus can't find anything