Jump to content
Fi8sVrs

Sudo 1.8.25p - Buffer Overflow Exploit

Recommended Posts

# Title: Sudo 1.8.25p - Buffer Overflow
# Author: Joe Vennix
# Software: Sudo
# Versions: Sudo versions prior to 1.8.26
# CVE: CVE-2019-18634
# Reference: https://www.sudo.ws/alerts/pwfeedback.html
 
# Sudo's pwfeedback option can be used to provide visual feedback when the user is inputting 
# their password. For each key press, an asterisk is printed. This option was added in 
# response to user confusion over how the standard Password: prompt disables the echoing 
# of key presses. While pwfeedback is not enabled by default in the upstream version of sudo,
# some systems, such as Linux Mint and Elementary OS, do enable it in their default sudoers files.
 
# Due to a bug, when the pwfeedback option is enabled in the sudoers file, a user may be able to trigger a stack-based buffer overflow.
# This bug can be triggered even by users not listed in the sudoers file. There is no impact unless pwfeedback has been enabled.
 
The folowing sudoers configuration is vulnerable:
 
    $ sudo -l
    Matching Defaults entries for millert on linux-build:
        insults, pwfeedback, mail_badpass, mailerpath=/usr/sbin/sendmail
 
    User millert may run the following commands on linux-build:
        (ALL : ALL) ALL
 
# Exploiting the bug does not require sudo permissions, merely that pwfeedback be enabled. 
# The bug can be reproduced by passing a large input to sudo via a pipe when it prompts for a password.
 
    $ perl -e 'print(("A" x 100 . "\x{00}") x 50)' | sudo -S id
    Password: Segmentation fault
 
If pwfeedback is enabled in sudoers, the stack overflow may allow unprivileged users to escalate to the root account.
 
#  0day.today [2020-02-05]  #

Source

  • Upvote 2

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...