Why would penetration testers use packet sniffers on a corporate network?

Penetration testers utilize packet sniffers on a corporate network primarily for the purpose of capturing and analyzing packets within traditional Ethernet LANs or WLANs. This technique allows testers to see the actual data being transmitted across the network, which can include sensitive information, protocols in use, and potential vulnerabilities in communication. By examining this data, penetration testers can identify security weaknesses, such as unencrypted data or improperly configured devices, which could be exploited by malicious actors.

The ability to analyze packet data is crucial for understanding how the network operates and where it may be susceptible to attacks. Penetration testers can discover feasible attack vectors by identifying unprotected credentials, unauthorized protocol usage, or misconfigured devices, ensuring that these vulnerabilities are addressed to enhance the overall security posture of the organization.

In contrast, managing user access and permissions, establishing VPN connections, or blocking unauthorized traffic do not directly involve the core functionality of packet sniffing. These activities are associated with network management or security practices but do not encompass the packet analysis aspect that is central to the activities of penetration testers.