Currently, many tools are available to analyze firmware security, such as Firmware Modification Kit, Angr binary analysis framework, Binwalk, ByteSweep, Binary Analysis Tool, Firmadyne, Firmwalker, Firmware Analysis Comparison Toolkit, etc.

Here, in this article, we will see the Top 10 Security Firmware Security Vulnerabilities found in IT devices.

(1) Unsupported core components

Updating and patching of IT devices help in mitigating known vulnerabilities. But sometimes, firmware updates may not support core components, which may negatively affect reliability and stability or result in data loss. Test it before any patch installation. Revert it if not supported and inform the manufacturer in forums.

(2) Sensitive URL disclosure

Sometimes sensitive URL is hardcoded in the source code of firmware. These URLs may leak sensitive data if exposed, which may risk the security of IT devices.

(3) Backdoor accounts

This vulnerability is a result of the ignorance of administrators. Backdoor accounts are helpful for admin users to forget their passwords. In that instance, a backdoor account helps reaccess admin accounts and acts as super admin. But if bad people know those backdoor accounts, the security of IT devices has been compromised. Hence, it is recommended that IT devices should not have any backdoor account that acts as a superuser. If required, proper authentication and log trail should be implemented to mitigate the risk of the account.

(4) Out-of-date core components

As time passes, security researchers are more interested in finding vulnerabilities in the IT devices available in the market. Manufacturers releases patches for those vulnerabilities to secure them. If patch installation not happens, it may be exploited by bad people. Hence, it is always recommended to patch IT devices released by manufacturers.

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(5) Hardcoded or easy to guess credentials

This vulnerability is easy to mitigate but hits it very hard if found by hackers. The administrator tends to give default username and password or easily guessable credentials for convenience if found by bad people, results in total compromise of the device. One of the bad practices to store credentials in code is that it compromises the whole set of IT devices. It is recommended not to store passwords or hashes in code.

(6) Sensitive information disclosure

This vulnerability again raises a significant risk to the security of the whole ecosystem. Sensitive information may be social security details, private information, etc.

(7) Admin web interface concerns

All web application related vulnerabilities applicable here. Check for issues by go web vulnerability scanner to identify who set of security issues. Also check for usage of vulnerable services (web, ssh, tftp, etc.) on IT device.

(8) Expired and/or self-signed certificates

Usage of expired and/or self-signed certificates raises a significant risk in the security of IT devices. If an attacker somehow accesses the network, the attacker can spoof the identity of the victim. On the usage of an expired certificate, transactions no longer secure by SSL/TLS. An attacker may intercept the traffic and extract sensitive information from users.

OWASP Mobile Top 10

(9) Same certificate used on multiple devices

Usage of the same certificate used on multiple devices raises a significant risk in IT devices’ security. If private is compromised, the whole set of devices are at risk. It is recommended to use the different certificates on devices.

(10) Encryption key exposure

Cryptographic mechanisms are responsible for the confidentiality and integrity of IT devices. But if encryption keys are exposed in any way, the whole security is gone.

Conclusion

Firmware security is one of the critical aspects of the security of IT devices. It is recommended to follow best practices released by manufacturers and different security communities while configuring IT devices.

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Q. What is a Blockchain?

Ans: Blockchain is a technology that helps in the peer-to-peer transfer of digital information and assets without any middlemen or intermediaries. Blockchain relied on immutable records of the distributed database. Blockchain technology is currently can be used in many applications such as finance, manufacturing, public distribution, healthcare, and other sectors.

Q. What is Bitcoin?

Ans: A person or a group of people (still suspense is there), called Satoshi Nakamoto, introduced a new digital currency called bitcoin, based on blockchain technology. Bitcoin enables people to transfer money anonymously from one point to another without any central authority (decentralized network). Please remember Bitcoin is not recognized by many countries and transaction in Bitcoins is illegal in some countries.

Q. As there is no central authority in the case of digital currency called Bitcoin, then how did Bitcoin realize trust and security among people?

Ans: Bitcoin implements a software program based on blockchain, that helps in validating, verifying, and building consensus in new infrastructure for transferring digital currency. The creation of every transaction in an immutable ledger is the basic building block of trust and security in blockchain infrastructure. Bitcoin uses cryptographic mechanisms to validate the integrity of transactions.

Q. What is a smart contract?

Ans: A smart contract is a software code and is a part of the blockchain node. The execution of smart code depends on the message which embeds in the transaction. It is used to provide conditional operations for the execution of transactions.

Q. Which language is used to write the smart contract?

Ans: Solidity is a high-level language that can be used to write the smart contract and compile it into bytecode.

Q. What is the basic structure of blockchain?

Ans: Transaction is the basic structure of the blockchain. Later, the same transaction is validated and broadcast in an immutable ledger. Many transactions form a box, and many boxes form a chain through a digital data link.

Q. What is Unspent Transaction Output (UTXO)?

Ans: UTXO is used as an input in a new transaction. It contains the following information:

• unique identifier of the transaction that created the UTXO
• Index of this UTXO in the transaction’s output list
• Value
• Optional: conditions under which output can be spent

Q. What are the advantages of blockchain technology?

Ans: Advantages:

1. It helps build trust among unknown people by ensuring the CIA triad, i.e., confidentiality, integrity, and availability.
2. Create logs of the transaction in an immutable ledger.
3. Able to send and receive money without any centralized authority (e.g., bitcoin).

Q. What is the Ethereum blockchain?

Ans: Ethereum blockchain is considered the mother of all blockchains. In 2013, Ethereum founders introduced a framework for code execution and were based on the concept of Smart Contracts.

Q. Is there any difference between Bitcoin Stack and Ethereum Stack?

Ans: Yes, the usage of smart contracts is the major difference between Bitcoin Stack and Ethereum Stack.

Q. What are the types of Blockchain networks?

Ans: Blockchain networks can be categorized into 3 types

(a) Public blockchains: This type of network can be accessed by the general public and make transactions. Bitcoin and Ethereum are two popular public blockchains.

(b) Private blockchains: As the name indicates, the only person that is allowed by network administrators is able to participate and make transactions.

(c) Consortium blockchains: It is considered a semi-decentralized network. Here, similar to the private blockchain, it also required network administrator permission, but it is controlled by many companies that operate each node on such a network.

Q. What are the Permissionless and Permissioned Blockchain?

Ans:

In a Permissionless blockchain, anyone can publish a new block. It is like a public internet where anyone can participate in a free manner.

In a Permissioned blockchain, some nodes can publish a new block. It is controlled by some nodes and restricted access. It is like a corporate intranet where only restricted people can participate in a restricted manner.

Q. What are the main components of Blockchain technology?

Ans: Main components of Blockchain technology are as follows:

• Cryptographic hash functions – method to convert any input into a unique output
• Transactions – interactions between two nodes
• Asymmetric-key cryptography
• Addresses – an alphanumeric string of characters to identify a user
• Ledgers – a collection of transactions
• Blocks – contains a cryptographic hash of the previous block, a timestamp, and transaction data

Q. What skills are required to become a blockchain developer?

Ans: To learn the development of the blockchain-based system, the following technology/concepts are required:

• Basics of Blockchain
• Cryptography concepts
• good command of at least one programming language (e.g. C++, Java, C#, Solidity, Scala, Kotlin, etc.)
• Concept of distributed ledger
• Concept of Networking

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CGI Scripts Interview Questions & Answers

Q1. What is a CGI Script?

Ans:

• CGI stands for Common Gateway Interface.
• It is a program that runs on a web server.
• It helps in creating interactive web pages dynamically based on inputs provided by the user.
• CGI scripts can be written in any language.
• Reside in a special directory in the webserver, typically “cgi-bin”.

Q2. Which computer language is generally used to write CGI scripts? 

Ans: Remember the fact that CGI scripts can be written in any language. But CGI scripts are generally written in the:

• Perl scripts
• C/C++ programs
• Unix Scripts

Q3. What does the REQUEST_METHOD environment variable specify?

Ans: It specifies whether we are using the GET or the POST method to send data to the server.

Q4. How does the form data get accessed in POST?

Ans: As a continuous stream of bytes from standard input, the number of bytes is stored in the content length environment variable.

Q5. Why is the POST method more secure as compared to the GET method?

Ans: In the GET method, data is sent as part of the URL. Hence, browser history and logs are stored in plaintext.  While in the POST method, parameters are not stored in browser history and server logs.

Q6. How do the CGI scripts know that the form data received has been URL encoded?

Ans: CONTENT_TYPE environment variable.

Q7. What is the function of the UNIX command “finger”?

Ans: “finger” command is used to display the following information:

• Login name
• Full name
• Office location
• Phone number
• Login time
• Idle time
• Project files

Q8. List out the differences between an interpreted language and a compiled language.

Ans:

Interpreted Language	Compiled Language
An interpreted language is parsed, interpreted and executed each time on run.	First source code is compiled, then executed.
Javascript, Python	Assembler, COBOL, C/C++
Less efficient	More efficient
Interpreted language produces the result from program	Compiler produces a program written in assembly language

Q9. How does the form data get accessed in GET, and in what form?

Ans: As a continuous stream of bytes from standard input, the number of bytes is stored in the content length environment variable.

Q10. Is there any difference between the CGI script and Java?

Ans:

CGI	JAVA
The protocol used to run programs on web servers.	Java is having its own standard APIs to, run the programs on web servers.
Not very scalable and secure.	Object-oriented and secure.
Platform dependent.	Platform independent.
No provision for separation between the presentation and business logic.	Java defines the clear separation between presentation and business logic.

Q11. Why do Programmers prefer to use Perl language for CGI?

Ans: There are many reasons behind the use of Perl language for CGI but we will discuss some important points:

• As Perl is interpreted language, you can easily do debugging while programming CGI. No compilation is needed to perform each task.
• Perl is quite a good choice for doing socket programming.
• Perl decently manages strings by the mechanism of memory allocation and deallocation.
• Perl has rich functionality for pattern matching.

Q12. What is the one main disadvantage of using Perl for CGI programming?

Ans: Some web applications are meant for only speed. If you want super fast speed for your web application, you must consider programming in a compiled language like C.

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Q1. Define OSI layers.

Ans: OSI stands for Open System Interconnection. There are 7 layers in the OSI model and each layer has a different capability. OSI model helps networking professionals in understanding information flow from one source to destination. Although the OSI model does not perform any function in the networking process.

Remember, all devices and software applications use the OSI model to explain data flow between source and destination.

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Q2. Are there any alternative models to the OSI model? If yes, define it.

Ans: TCP/IP is the alternate model that also explains the information flow in the network. It is a simpler representation compared to the OSI model but contains fewer details of protocols than the OSI model.

Q3. What is the difference between TCP and UDP?

Ans: TCP and UDP: Comparison between Two Transport Protocols

Q4. What is the importance of the Physical Layer in the OSI model?

Ans: Physical layer is the first layer that connects systems physically and resembles the actual transfer of information from source to destination in the form of bitstream – electrical impulse, light, or radio signal. In simple words, it accepts a frame from the data link layer and converts it into bits. It also accepts bits from the physical medium and converts them into the frame. It helps in managing the Network Interface Card’s (NIC) hardware interface such as cabling, voltage levels, etc.
Standard protocols for this layer are EIA/TIA-232, EIA/TIA-449, X.21, HSSI, V.24, V.35, and SONET.

Q5. Which layers perform error detection and flow control?

Ans:  On receiving and while transmission of information, Layer 2 – Data Link layer decoded and encoded data into bits. This layer is the firmware layer of NIC. It converts datagrams into frames and also adds start and stop flags to each frame.

The data link layer is further divided into two sublayers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. This layer also performs error checking and flow control.

Q6. How does the network administrator detect the problem?

Ans: Network administrators may use the OSI model to understand the information flow and try to find problems by further understanding each layer’s protocols. Experience in networking reduces the time to find problems and resolve them. Network problems may be a loose physical connection, configuration issues, etc.

Click Here for Practical Examples of OpenSSL 

Q7. What is the difference between flow control and error control?

Ans: As the name suggests, flow control controls the rate of information transmitted to ensure the receiver’s efficient delivery of data. While error controls check and correct errors in the data bits and packets.

Q8. What is Data encapsulation?

Ans: Data encapsulation is a process of adding extra information at each layer of the OSI model while information flow from one host to another host. Information such as source and destination address, protocol information, type of data, etc.

Q9. What are the differences between the MAC sublayer and LLC sublayer?

Ans: MAC sublayer stands for Media Access Control layer.  MAC address works on Layer 2- Data Link Layer. This layer controls the permission of data to transmit.

LLC sublayer stands for Logical Link Control layer. This layer controls frame synchronization, flow control, and error checking.

Q10. What is the difference between half-duplex and full-duplex?

Ans: In a half-duplex, information can flow in both directions but not simultaneously. While in full-duplex, information can flow in both directions simultaneously.

Miscellaneous Questions

Q. Explain the role of the presentation layer.

Ans: The presentation layer is number 6 in the OSI model. On the sending system, It will receive data from the application layer, transform and encrypt in a legible format and pass it to the session layer. On the receiving system, simply converts the incoming data from the session layer so that data is readable at the application layer.

Q. Explain the role of the Transport layer.

Ans: The presentation layer is number 4 in the OSI model. I am listing different roles of the transport layer as mentioned below:

1. to check the reliability of data
2. flow control of data
3. to check the order of data
4. ensure the reliability of data
5. to prevent congestion

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