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Stack 2 Source Code The following is the source code for Stack 2 challenge #include <stdlib.h> #include <unistd.h> #include <stdio.h> #include <string.h> int main(int argc, char **argv) { volatile int modified; char buffer[64]; char *variable; variable = getenv("GREENIE"); if(variable == NULL) { errx(1, "please set the GREENIE environment variable\n"); } modified = 0; strcpy(buffer, variable); if(modified == 0x0d0a0d0a) { printf("you have correctly modified the variable\n"); } else { printf("Try again, you got 0x%08x\n", modified); } } Challenge In this challenge the value of environment variable GREENIE is being copied to buffer and hence we need to set GREENIE environment variable with out playload that will overflow the buffer and will modify the value of modified to 0x0d0a0d0a so this can be done using export statement along with little python magic.

Stack 1 Source Code The following is the source code for Stack 1 Challenge #include <stdlib.h> #include <unistd.h> #include <stdio.h> #include <string.h> int main(int argc, char **argv) { volatile int modified; char buffer[64]; if(argc == 1) { errx(1, "please specify an argument\n"); } modified = 0; strcpy(buffer, argv[1]); if(modified == 0x61626364) { printf("you have correctly got the variable to the right value\n"); } else { printf("Try again, you got 0x%08x\n", modified); } } Challenge In this challenge we needed to modify the modified variable with a specific value (i.

Stack 0 Source Code Here is the source code for the Stack 0 challenge #include <stdlib.h> #include <unistd.h> #include <stdio.h> int main(int argc, char **argv) { volatile int modified; char buffer[64]; modified = 0; gets(buffer); if(modified !