-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 XPD - XPD Advisory https://xpd.se Crypto implementation flaws in Pacom GMS System Advisory ID: XPD-2015-001 CVE reference: CVE-2014-3260 Affected platforms: Pacom 1000 CCU ("Base Station") and Controllers (RTU) Version: All versions are affected Date: 2013-Oktober-10 Security risk: High Vulnerability: Crypto implementation flaws in Pacom GMS System Researcher: Joachim Strombergson, Fredrik Soderblom, Peter Norin Vendor Status: Notified / Patch available Vulnerability Disclosure Policy: https://xpd.se/advisories/xpd-disclosure-policy-01.txt Permanent URL: https://xpd.se/advisories/XPD-2015-001.txt ===================================================================== Summary: The Pacom 1000 CCU and controllers (RTU) is used in security alarm installations all over the world. The flaws we have found can bypass the security of any unpatched installation. "The purpose of a Pacom Controller is to control, monitor, and maintain security for a remote site. It is located at the site itself and performs all alarm and door control functions." - http://www.pacom.com/field-controllers.php "Pacom security solutions are installed in over twenty countries on seven continents." - http://www.pacom.com/our-customers.php Detailed description: The Pacom 1000 implementation have several serious implementation flaws. These vulnerabilities could in a worst case scenario lead to a full compromise of the protocol between the controller and the base station, rendering an alarm system useless. Potentially a large number of sites could be affected by the described flaws. PRNG: The PRNG used is of a type known as a Linear Congruential Generator. This type of generator are known to provide random numbers with less than perfect uniform distribution. The PRNG is a 16-bit generator. This means that the generator can only generate 2**16 numbers in a sequence before it must be reseeded. There is no information about how the generator is seeded from start nor how it is reseeded. A simulation in Dieharder shows that the used algorithm fails every test except for one, where it receives the result 'Weak'. The Linear Congruential Generator can be broken by observing values generated by consecutive iterations of the PRNG. The system creates 32-bit random numbers by extracting 8-bits from four consecutive 16-bit words numbers generated by the PRNG. This means that by observing a single 32-bit word, an attacker has in fact half the state information (8 out of 16 bits) from four iterations of the generator. MAC: A Message Authentication Code (MAC) is generated and added to each message sent between CCU and Controller. The MAC generator generator used is not based on any well-known secure MAC functionality such as HMAC or OMAC. Furthermore the generated MAC is only 32 bit. Master Code: There is a functionality for substitution detection. According to Pacom the functionality is based on a proprietary Pacom encryption method. Key to the functionality is a a 24-bit randomly generated value called Master Code. The Master Code is also used to generate the 128-bit AES key used with the substitution detection algorithm. Hence the effective strength of the key is not 128 bits, nor 104 bits (128 - 24) but 24 bits. A very short key with low security. Unfortunately it appears that the aforementioned (16 bit only), less than optimal, PRNG is used to generate the Master Code, thus reducing it's effective strength to 16 bit. The Master Code is distributed from CCU to CPU-cards and other CCUs as well as GMS units (for logging purposes) in clear text. This means that the code potentially is sent unprotected over private networks, corporate networks, public networks etc. Substitution detection: According to Pacom documentation the "substitution detection involves appending a 128-bit check code to the controller heartbeat response messages. The check code is calculated from a combination of a hard-coded constant value, the controllers master code, and the message data. In essence it is another type of MAC, but one that employs the master code." The implementation of the substitution detection uses a "check code" which is said to be 128-bits long and is appended to response messages. However due to a design flaw, the code is only 64 bit. In total the heartbeat response message is 5 bytes (40 bits) long: Byte 1: The message type (e.g. heartbeat response) Byte 2: A value based on random numbers sent in the heartbeat command from the CCU Byte 3: The controller summary status Byte 4: The heartbeat sequence number (zero or one) Byte 5: Always zero Of the five bytes in the heartbeat response message, two bytes (4 and 5) are either one or zero, or always zero. Byte 3 is a simple status. So, of 40 bits, 32 bits are most likely predictable and the remaining 8 bits is probably choosen based on the weak PRNG. This means that a big part of the response message can be guessed. The so called "128-bit check code" is then calculated over these 5 bytes using the aforementioned flawed Master Code and a 2 byte address of the controller, forming a 40 bit key, which is used with a hard coded constant to form an AES-128 key. The resulting "128-bit check code" from the AES encryption is XOR:ed with its own cleartext. This means that there is a direct path from cleartext to ciphertext bypassing the AES encryption. This leaks information about the cleartext as well as opening up for chosen plaintext attacks. Hard coded constants: The security functionality uses several hard coded, secret constants for random number generation, MAC calculation, Substitution detection algorithm etc. Unfortunately, the way these constants are used, information about them are leaked through the very messages, which opens up for recovery of the constants. If the constants are recovered and thus system security is lost, the units must be reprogrammed in the field or even replaced. ===================================================================== Conclusion: We do not recommend relying on the security features in the system and the system should be viewed as an unprotected system. If the system is to be used, separate communication security mechanism should be added. However, the usage of hard coded constants in the units and the associated need for field service or replacement if a breach occurs, makes us recommend that the system needs severe redesign before it is ready for production use. We questions if the system has been designed with any knowledge of what has been known good security practices since at least 30 years, nor good engineering practice. ===================================================================== Versions affected: All versions of Pacom 1000 (CCU & RTU) - According to Pacom, this firmware will not be fixed. Customers are advised to switch to the EMCS platform instead. All versions of EMCS (Pacom .is) prior to 1.3 The vendor reports that the following versions are patched: EMCS (Pacom .is) version 1.3 and above ===================================================================== Credits This vulnerability was discovered and researched by Joachim Strombergson from Assured AB, Fredrik Soderblom and Peter Norin from XPD AB. ===================================================================== References https://en.wikipedia.org/wiki/Linear_congruential_generator https://en.wikipedia.org/wiki/Diehard_tests ===================================================================== History 2013-10-10 Initial Discovery 2013-10-22 Initial attempt to contact the vendor 2013-11-12 Reply from Niscayah, case is assigned to internal resource 2014-05-07 CVE-2014-3260 is assigned 2014-06-05 Draft of the advisory sent to the vendor 2014-09-01 Pacom notifies us that fixed firmware (EMCS only) is ready 2015-12-08 Public disclosure ===================================================================== About Assured Assured AB is a privately held company with headquarters in Gothenburg, Sweden. Established in 2015, Assured is an independant security consultancy firm that provides expert knowledge, advisory and design of IT- security solutions. http://assured.se About XPD XPD AB is a privately held company with Headquarters in Stockholm, Sweden. Established in 2002, XPD AB is an independent security consulting and research firm, with a focus on security and perimeter security solutions. https://xpd.se ===================================================================== Disclaimer and Copyright Copyright (c)2015 XPD AB and Assured AB. All rights reserved. This advisory may be distributed as long as its distribution is free-of-charge and proper credit is given. The information provided in this advisory is provided "as is" without warranty of any kind. XPD AB and Assured AB disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall XPD AB or Assured AB, or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if XPD AB or Assured AB, or its suppliers have been advised of the possibility of such damages. -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJWYCTaAAoJEH47YPoA7U9kecIQAJP3eHCA6zdz3sq1bAPg4JOc SBmq/auoraVpcucBzjVkGy8qtCF12mu0Gf2Kn6zwCtUcBmfjAo97HZYFx582ofOy K0ZGkA06tfGWJthDZ1eyeotQq9yBRLl1un1hGmrM/CvyRMp7KDd2jUptBps6Ddrk dl5a8+tMcQkedSV+dNDLwVpLWn8/hsDL8YjbZCeVomNtgceTb07hMv6zqrf3TgYZ yyq7xlLNzEyQSXyF0qF+yKsQ0HQyAnzQyoyzzYjeSbBBhvjeb/6x0S8t0QuP2Hqy cM+zNn/zzPoaubHFVUMi0tluhr/mqagrdmugmWG5cEfStmZYKJLkM/1EkFZDmlUF fuWQ/YrIgYU8twBwqzO+9iUdMM6gqRNaKIO5nN+1ivlYwxoVJ5N+gYCUbEZCGQac JDWGuYtHUpEzL/E2WrLq6iTpxutn1iAuyDM67/vsJaucLngLHJdW/iCIx4OVNdn4 caXMo4UZbJUzzu1OOCtCuYpUZHIbLuuVZkmb3ihj5UL/Z9OXyGKv4XpFed8xqydx FnB+dsnaG1HKyKIfNUVl7uiODEe2qiPUdmdY7J/0UWksYmoAPq77rmqhfEIH9jaU 0nq3frmUk70XdEjPG9oIr1Mw02ugIS8cYPM7zn57TskNnBnrlnO2PkBzSBOGJy08 NzycvpVV7wdtvgKeZHum =b7KM -----END PGP SIGNATURE-----