Information Leakage / Echo Service Detection

Description

The Chargen (Character Generator) service is a network service that operates on UDP (User Datagram Protocol) port 19. It was originally designed for testing and debugging purposes, generating a stream of characters that are sent back to the originating host. However, due to its potential for misuse, the Chargen service is considered a security risk.

A Remote Denial of Service (DoS) attack involving the Chargen UDP service typically involves sending a large number of requests to the Chargen port on a target system, causing it to respond with a stream of characters. The goal of the attacker is to overwhelm the target system's resources, leading to a denial of service for legitimate users.

Risks

The high volume of UDP responses generated by the Chargen service in response to a flood of requests can consume the target system's resources, leading to degraded performance or unresponsiveness.
The attack can saturate network bandwidth with unnecessary traffic, impacting the overall network performance.

An easy attack is ping-pong in which an attacker spoofs a packet between two machines running chargen. This will cause them to spew characters at each other, slowing the machines down and saturating the network.

Solution

Service Disabling: If the Chargen service is not required for legitimate purposes, consider disabling it. Disable the Chargen service on both individual hosts and network devices.
Firewall Configuration: Implement firewall rules to block incoming traffic on UDP port 19, especially if the Chargen service is not needed for legitimate purposes. This prevents external entities from exploiting the Chargen service on the target system.
Filtering at the Network Perimeter: Use network perimeter devices, such as routers or intrusion prevention systems, to filter or rate-limit UDP traffic on port 19. This can help mitigate the impact of a potential Chargen UDP DoS attack.