Background/Objectives: The wireless internet service, which has positioned as an important element to support all industries, can be connected to notebook computers and smartphones everywhere. Using wireless internet access increases, the risk of hacking also increases. Methods/Statistical analysis: There is information leakage accident by modulating DNS address of home router and hacking threats by using wireless router always exists Findings: In this paper, we search hacking techniques using vulnerabilities in wireless LAN, and analyze the need for security for wireless LANs through WEP encryption algorithms and improved encryption algorithms. Improvements/Applications: We also suggest countermeasures against hacking techniques such as DoS attacks, WEP Crack, and DNS Spoofing.