hook-test.py

#!/usr/bin/env python

import sys
import angr

p = angr.Project(sys.argv[1], load_options={'auto_load_libs': False})
s = p.factory.entry_state()

def malloc_print(state):
    print("Called malloc!")

def free_print(state):
    print("Called Free!")

p.hook_symbol('free', free_print)
p.hook_symbol('malloc', malloc_print)

pg = p.factory.path_group(s)
pg.explore()

test.c

/* compiled with gcc -o test test.c */

#include <stdlib.h>

int main(void)
{
    int* ptr = malloc(1024);
    free(ptr);
}