GEN:SID 1:268
Message DOS Jolt attack
Summary This event is generated when a remote attacker attempts to send large, fragmented IP packets to the internal network, indicating a Jolt Denial of Service (DoS) attack.
Impact Denial of service.
Detailed Information Jolt is a DoS attack characterized by large, fragmented IP packets that, when launched at a Windows system, can hang or crash the computer.
Affected Systems Windows 95
Windows 98
Windows NT
Windows 2000
Attack Scenarios An attacker sends oversized, fragmented IP packets to a target computer. If the computer is running an unpatched version of Windows, it may crash.
Ease of Attack Simple.
Corrective Action Install the latest patches available for your operating system.

Implement a packet-filtering firewall to block inappropriate traffic to the network.
Additional References  
Rule References cve: 1999-0345