Protection and Security in RTOS

Differences between OS and RTOS: 

Flowchart Explaining Structure of a typical Realtime Operating System 

                                                                                      

Operating systems are the interface between the hardware of the system and the applications running on the system. A computing environment with the capacity to respond to events within a strictly defined time frame is presented by real-time operating systems (RTOS). Modern embedded systems for particular domains (like aerospace, industrial control, defense, and medicine) contain safety-critical programmes whose failure would have disastrous consequences. These systems use RTOS instead of general-purpose operating systems to function in challenging and dynamic environments. In the computers we use General Purpose Operating Systems (GPOS) while in embedded systems we use Real Time Operating Systems (RTOS).

Classical Architecture of an RTOS

When the general-purpose systems such as the desktop computer is turned on, the general-purpose operating system takes the control of the desktop machine and then allows the user to run the application. In desktop computers the user application program separately compiles and links from the general-purpose operating system. In an embedded system usually embedded software links with RTOS. At the boot up time, embedded software gets control first and then it then starts the RTOS. 

 

How is RTOS vulnerable?

RTOS is heavily used in Embedded system networks as it provides much needed flexibility in resource management, task scheduling and also provide security to the system. A poorly designed RTOS that is deployed over a network system can exploited.  An example of an attacker attempting to access private data that is sent across the network. This method is called data sniffing. If appropriate encryption techniques are not used, the attacker may be able to sniff the sensitive data once they have gained access to the network. While monitoring the transmission, a hacker may get all the information and control commands, which they could then use to transmit erroneous messages. The integrity of the data transmitted over the network may likewise be compromised by an attacker tampering with it. It is possible to make the saved data on the remote servers a target. A system's memory and processor resources can be managed by the operating system. If the Operating System is not created with security in mind, it will always be open to attack and incapable of stopping and limiting the harm caused by unauthorised access. The system's availability, validity, confidentiality, and integrity may all be jeopardised by the attacks. And that's the reason built in security for RTOS are now widely employed in all sectors of society where it is necessary to protect linked devices' performance. These sectors include, among others, linked houses, connected medical equipment, vital industrial/infrastructure control systems, and connected cars. 

 

One of the most frequent and perhaps most harmful forms of attacks on contemporary computer system networks is code injection. These attacks operate by installing and running arbitrary code on the targets' computers. Typically, the goal is to take over the machine's programme counter (PC). This gives the attacker the ability to alter the order in which instructions are executed and trick the computer into running malicious code that the attacker has added. This injected code may be natively executable machine code, intermediate byte-code, or source code for an interpreted scripting language. Such code may be created for an instant attack, where it runs immediately (such as stealing user session data or running a modified SQL query), or it may run later. One such peculiar instance included an EV charger. By switching the "Branch if equal" (BEQ) assembly instruction to "Branch if not equal" (BNE) in debug mode, it was possible to get around the password authentication process for EV chargers. This gives the attackers the ability to enter false passwords and yet access the system code of the device.

 

 

How are these security concerns dealt in modern RTOS systems?

Use of Multilevel Security Method:

A highly favoured approach for resolving security challenges is the Multiple Independent Level of Security method. It primarily operates on the divide-and-conquer approach, where a process is separated into numerous independent levels and security policies are applied to independent kernels. This prevents hackers from breaking the system and isolates the problem, ensuring that the failure of one partition won't have an impact on the other. 

 

Use of secure Authentication framework:

A secure user identification and authorisation method are used in the RTOS system to confirm a user. The embedded device is possibly accessible by unauthorised users if they are not correctly identified and authenticated. An embedded device's user accounts shouldn't be static in nature. To prevent automated harmful assaults, features that allow for the separation of user identities for internal web management, internal console access, as well as remote web management and remote console access, should be available. For all services, all access must be permitted and users must only have the minimal privileges required. For instance, if command line shell access is necessary, make sure it is safe, password-protected, and has the lowest user permission level available. The RTOS has a tool for preventing malicious programmes from adversely influencing system performance thanks to the use of privilege levels. All forms of communication should employ IPSec, SSH, SSL, or VPN access as necessary. It is better to presume that all data is sensitive and that data transfer can and will be intercepted.

 

RTOS network firewall:

Any device with a network connection should be running with a firewall in place because modern RTOS include network firewall features. Since embedded devices are increasingly connected to the same networks as larger size devices, firewalls are considered standard practise for desktop and server systems. A firewall is a good first line of defence against network attacks and should only permit communication through necessary TCP/IP ports. Only ports that are specifically configured to be open and accessible for connection are permitted by the firewall, which makes sure that all non-essential ports and services are shut off. 

Conclusion

The security aspect of RTOS needs to be given top priority because it is utilised in applications and industries where activities must be done rapidly and without delay. Any security breach to the system could disrupt operations and have disastrous effects on the environment and human safety. The security and dependability of safety-critical systems are examined in-depth and methodically in this essay. In the context of safety-critical RTOS, we emphasise the best practises, most recent research initiatives, and their viability. We contrast the solutions qualitatively and go over their advantages and disadvantages.