ICMP Echo Reply without Echo
| icmp-unsolicited-echo-reply (8014) |  Low Risk |
Description:
This computer received an ICMP echo reply (commonly called a ping) without having first sent a ping request. This event may occur for one or more reasons:
- Firewall scanning: Any administrator or intruder may use this technique to scan systems behind a corporate firewall. Most corporate firewalls allow ping/echo repsonses to pass through. Otherwise, ping programs won't work correctly. However, when a router within the corporation attempts to forward the packet to a nonexistent host, it sends back an "unreachable" message to the sender. In this manner, somebody can map the structure of the network behind a corporate firewall.
- Trojan communication: ICMP traffic is a common way of communicating with Trojan horse programs. This method is effective because it passes through firewalls.
- Denial of Service (DoS) attacks: Ping floods are also used as a direct DoS mechanism. The goal is to flood you with traffic (especially traffic that pierces firewalls) to slow down the Internet connection.
- Spoof by-products: An attacker could be spoofing your IP address. They could be sending pings to a target claiming that these pings are from you. You would then see these replies. There is no reliable method to determine who is doing this.
Consequences:
Data Manipulation
Remedy:
Verfiy the source of the traffic and that no rogue applications are running.
References:
- CVE-1999-0454: A remote attacker can sometimes identify the operating system of a host based on how it reacts to some IP or ICMP packets, using a tool such as nmap or queso.
Platforms Affected:
- Microsoft Windows
- Unix Unix
Reported:
Not available
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