The security analyst observed that 192.168.12.21 made a TCP connection to 209.132.177.50. This can be inferred from the packet capture output, which shows the following sequence of packets:
Packet 1: A SYN packet from 192.168.12.21 to 209.132.177.50 on port 80 (HTTP). This is the first step of the TCP three-way handshake, where the source initiates a connection request to the destination.
Packet 2: A SYN-ACK packet from 209.132.177.50 to 192.168.12.21 on port 80 (HTTP). This is the second step of the TCP three-way handshake, where the destination acknowledges and accepts the connection request from the source.
Packet 3: An ACK packet from 192.168.12.21 to 209.132.177.50 on port 80 (HTTP). This is the third and final step of the TCP three-way handshake, where the source confirms and completes the connection establishment with the destination.
These packets indicate that a TCP connection was successfully established between 192.168.12.21 and 209.132.177.50 on port 80.