Android逆向之绕过双进程保护

修改$AOSP/bionic/libc/bionic/fork.c，让程序fork失败即可，修改的代码如下:

#include 
#include 
#include 
#include "pthread_internal.h"
#include "bionic_pthread.h"
#include "cpuacct.h"

extern int  __fork(void);

#define BUF_LEN 512

int block()
{
    char buf[BUF_LEN] = {0};
    char cmd[128] = {0};
    sprintf(cmd , "/proc/%d/cmdline" , getpid());
    int fd = open(cmd , O_RDONLY);
    read(fd , buf , BUF_LEN);
    close(fd);
    char targetPath[BUF_LEN] = {0};
    sprintf(targetPath , "/data/data/%s" , buf);
    if (access(targetPath , F_OK) == 0)
    {
         return 1;
    }
    return 0;
}

int  fork(void)
{
    int  ret;
    if (block())
    {
        return -1;
    }
//......
}

虽然这种小技巧很容易在以后的加固版本会被针对，但是至少目前是有效的