Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 05 Feb 2020 11:31:55 -0500
From: "Larry W. Cashdollar" <larry0@...com>
To: Open Security <oss-security@...ts.openwall.com>
Subject: Re: CVE-2019-18901: mariadb: possible symlink attack
 for the mysql user in the SUSE specific mysql-systemd-helper script

Hello Matthias,

That chmod 640 might be interesting if applied to /etc/shadow.  It could allow some users to read the password hashes.

On 2/5/20, 7:46 AM, "Matthias Gerstner" <mgerstner@...e.de> wrote:

    Hello list,
    
    in the course of a review of the mariadb packaging in the SUSE Linux
    distribution I discovered that a SUSE specific helper script
    "mysql-systemd-helper" unsafely operates with root privileges in
    the /var/lib/mysql directory [1].
    
    During initial package installation and during upgrade scenarios the
    file /var/lib/mysql/mysql_upgrade_info is created/overwritten and
    modified using the following shell commands:
    
    ```
    echo -n "$MYSQLVER" > "$datadir"/mysql_upgrade_info
    chmod 640 "$datadir/mysql_upgrade_info"
    ```
    
    Since the unprivileged mysql user owns the parent directory it can
    remove this file and replace it with a symlink to write/overwrite in
    privileged file systems locations. This could mostly be used for
    denial-of-service purposes, a full privilege escalation should not be
    easily achieved by this vulnerability, since the file content cannot be
    controlled by a potential attacker.
    
    Future SUSE mariadb packages will keep this file in a safe location in
    /var/lib/misc. Older, still supported packages will be fixed soon.
    
    Cheers
    
    Matthias
    
    References
    ----------
    
    [1]: https://bugzilla.suse.com/show_bug.cgi?id=1160895
    
    -- 
    Matthias Gerstner <matthias.gerstner@...e.de>
    Dipl.-Wirtsch.-Inf. (FH), Security Engineer
    https://www.suse.com/security
    Phone: +49 911 740 53 290
    GPG Key ID: 0x14C405C971923553
    
    SUSE Software Solutions Germany GmbH
    HRB 36809, AG Nürnberg
    Geschäftsführer: Felix Imendörffer
    


Powered by blists - more mailing lists

Your e-mail address:

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.