ExecShield is security Linux kernel patch to avoid worms and other problems.
Wikipedia has more information about Exec Shield project:
Exec Shield is a project that got started at Red Hat, Inc in late 2002 with the aim of reducing the risk of worm or other automated remote attacks on Linux systems. The first result of the project was a security patch for the Linux kernel that adds an NX bit to x86 CPUs. While the Exec Shield project has had many other components, some people refer to this first patch as Exec Shield.
Task: Disable ExecShield protection
Type the following command as root user:
# sysctl -w kernel.exec-shield=0
You can disable it permanently system-wide after each and every reboot by adding following line to /etc/sysctl.conf file:
# vi /etc/sysctl.conf
Append following line
kernel.exec-shield=0
Save and close the file. Please note that I don’t recommend disabling ExecShild protection.
Read more: nix Craft