Have an account?
It looks like you're new here. If you want to get involved, click one of these buttons!
Apply for Membership
Who's Online (1)
Looking to introduce yourself? Look no further, and click here! We also have IRC! [irc.evilzone.org #iexploit]
Questions to ask during an infosec interview
Found this nice article here which shows some good questions to be asked during an interview for an information security position and how to/not to answer. By Daniel Miesser.
What follows is a list of questions for use in vetting candidates for positions in Information Security. Many of the questions are designed to get the candidate to think, and to articulate that thought process in a scenario where preparation was not possible. Observing these types of responses is often as important as the actual answers.
Iâ€™ve mixed technical questions with those that are more theory and opinion-based, and they are also mixed in terms of difficulty. A number of trick questions are included, but the goal there is to expose glaring technical weakness, not to be cute. I also include with each question a few words on expected responses.
Where do you get your security news from?
Here Iâ€™m looking to see how in tune they are with the security community. Answers Iâ€™m looking for include syndication feeds for solid sites like liquidmatrix, packetstorm, rootsecure, secguru, astalavista, whitedust, internet storm center, etc. The exact sources donâ€™t really matter. What does matter is that he doesnâ€™t respond with, â€œI go to the CNET website.â€, or, â€œSteve Gibsonâ€™s home pageâ€. Itâ€™s these types of answers that will tell you heâ€™s likely not on top of things.
If you had to both encrypt and compress data during transmission, which would you do first, and why?
If they donâ€™t know the answer immediately itâ€™s ok. The key is how they react. Do they panic, or do they enjoy the challenge and think through it? I was asked this question during an interview at Cisco. I told the interviewer that I didnâ€™t know the answer but that I needed just a few seconds to figure it out. I thought out loud and within 10 seconds gave him my answer: â€œCompress then encrypt. If you encrypt first youâ€™ll have nothing but random data to work with, which will destroy any potential benefit from compression.â€
Whatâ€™s the difference between HTTP and HTML?
Obviously the answer is that one is the networking/application protocol and the other is the markup language, but againâ€“the main thing youâ€™re looking for is for him not to panic.
How does HTTP handle state?
It doesnâ€™t, of course. Not natively. Good answers are things like â€œcookiesâ€, but the best answer is that cookies are a hack to make up for the fact that HTTP doesnâ€™t do it itself.
What exactly is Cross Site Scripting?
Whatâ€™s the difference between stored and reflected XSS?
Stored is on a static page or pulled from a database and displayed to the user directly. Reflected comes from the user in the form of a request (usually constructed by an attacker), and then gets run in the victimâ€™s browser when the results are returned from the site.
What are the common defenses against XSS?
Input Validation/Output Sanitization, with focus on the latter.
Whatâ€™s the difference between symmetric and public-key cryptography
Standard stuff hereâ€“single key vs. two keys, etc, etc.
In public-key cryptography you have a public and a private key, and you often perform both encryption and signing functions. Which key is used for which function?
You encrypt with the other personâ€™s public key, and you sign with your own private. If they confuse the two, donâ€™t put them in charge of your PKI project.
What kind of network do you have at home?
Good answers here are anything that shows you heâ€™s a computer/technology/security enthusiast and not just someone looking for a paycheck. So if heâ€™s got multiple systems running multiple operating systems youâ€™re probably in good shape. What you donâ€™t want to hear is, â€œI get enough computers when Iâ€™m at work..â€ Iâ€™ve yet to meet a serious security guy who doesnâ€™t have a considerable home network.
What is Cross-Site Request Forgery?
Not knowing this is more forgivable than not knowing what XSS is, but only for junior positions. Desired answer: when an attacker gets a victimâ€™s browser to make requests, ideally with their credentials included, without their knowing. A solid example of this is when an IMG tag points to a URL associated with an action, e.g.
. A victim just loading that page could potentially get logged out from foo.com, and their browser would have made the action, not them (since browsers load all IMG tags automatically).
How does one defend against CSRF?
Nonces required by the server for each page or each request is an accepted, albeit not foolproof, method. Again, weâ€™re looking for recognition and basic understanding hereâ€“not a full, expert level dissertation on the subject. Adjust expectations according to the position youâ€™re hiring for.
What port does ping work over?
A trick question, to be sure, but an important one. If he starts throwing out port numbers you may want to immediately move to the next candidate. Hint: ICMP is a layer 3 protocol (it doesnâ€™t work over a port) A good variation of this question is to ask whether ping uses TCP or UDP. An answer of either is a fail, as those are layer 4 protocols.
How exactly does traceroute/tracert work at the protocol level?
This is a fairly technical question but itâ€™s an important concept to understand. Itâ€™s not natively a â€œsecurityâ€ question really, but it shows you whether or not they like to understand how things work, which is crucial for an Infosec professional. If they get it right you can lighten up and offer extra credit for the difference between Linux and Windows versions.
The key point people usually miss is that each packet thatâ€™s sent out doesnâ€™t go to a different place. Many people think that it first sends a packet to the first hop, gets a time. Then it sends a packet to the second hop, gets a time, and keeps going until it gets done. Thatâ€™s incorrect. It actually keeps sending packets to the final destination; the only change is the TTL thatâ€™s used. The extra credit is the fact that Windows uses ICMP by default while Linux uses UDP.
If you were to start a job as head engineer or CSO at a Fortune 500 company due to the previous guy being fired for incompetence, what would your priorities be? [Imagine you start on day one with no knowledge of the environment]
We donâ€™t need a list here; weâ€™re looking for the basics. Where is the important data? Who interacts with it? Network diagrams. Visibility touch points. Ingress and egress filtering. Previous vulnerability assessments. Whatâ€™s being logged an audited? Etc. The key is to see that they could quickly prioritize, in just a few seconds, what would be the most important things to learn in an unknown situation.
As a corporate Information Security professional, whatâ€™s more important to focus on: threats or vulnerabilities?
This one is opinion-based, and we all have opinions. Focus on the quality of the argument put forth rather than whether or not they they chose the same as you, necessarily. My answer to this is that vulnerabilities should usually be the main focus since we in the corporate world usually have little control over the threats.
Another way to take that, however, is to say that the threats (in terms of vectors) will always remain the same, and that the vulnerabilities we are fixing are only the known ones. Therefore we should be applying defense-in-depth based on threat modeling in addition to just keeping ourselves up to date.
Both are true, of course; the key is to hear what they have to say on the matter.
Describe the last program or script that you wrote. What problem did it solve?
All we want to see here is if the color drains from the guyâ€™s face. If he panics then we not only know heâ€™s not a programmer (not necessarily bad), but that heâ€™s afraid of programming (bad). I know itâ€™s controversial, but I think that any high-level security guy needs some programming skills. They donâ€™t need to be a God at it, but they need to understand the concepts and at least be able to muddle through some scripting when required.
What are Linuxâ€™s strengths and weaknesses vs. Windows?
Look for biases. Does he absolutely hate Windows and refuse to work with it? This is a sign of an immature hobbyist who will cause you problems in the future. Is he a Windows fanboy who hates Linux with a passion? If so just thank him for his time and show him out. Linux is everywhere in the security world.
Whatâ€™s the difference between a threat, vulnerability, and a risk?
As weak as the CISSP is as a security certification it does teach some good concepts. Knowing basics like risk, vulnerability, threat, exposure, etc. (and being able to differentiate them) is important for a security professional. Ask as many of these as youâ€™d like, but keep in mind that there are a few differing schools on this. Just look for solid answers that are self-consistent.
Cryptographically speaking, what is the main method of building a shared secret over a public medium?
Diffie-Hellman. And if they get that right you can follow-up with the next one.
Whatâ€™s the difference between Diffie-Hellman and RSA?
Diffie-Hellman is a key-exchange protocol, and RSA is an encryption/signing protocol. If they get that far, make sure they can elaborate on the actual difference, which is that one requeres you to have key material beforehand (RSA), while the other does not (DH). Blank stares are undesirable.
What kind of attack is a standard Diffie-Hellman exchange vulnerable to?
Man-in-the-middle, as neither side is authenticated.
Whatâ€™s the goal of information security within an organization?
This is a big one. What I look for is one of two approaches; the first is the Ã¼ber-lockdown approach, i.e. â€œTo control access to information as much as possible, sir!â€ While admirable, this again shows a bit of immaturity. Not really in a bad way, just not quite what Iâ€™m looking for. A much better answer in my view is something along the lines of, â€œTo help the organization succeed. â€This type of response shows that the individual understands that business is there to make money, and that we are there to help them do that. It is this sort of perspective that I think represents the highest level of security understandingâ€”-a realization that security is there for the company and not the other way around.
Are open-source projects more or less secure than proprietary ones?
The answer to this question is often very telling about a given candidate. It shows 1) whether or not they know what theyâ€™re talking about in terms of development, and 2) it really illustrates the maturity of the individual (a common theme among my questions). My main goal here is to get them to show me pros and cons for each. If I just get the â€œmany eyesâ€ regurgitation then Iâ€™ll know heâ€™s read Slashdot and not much else. And if I just get the â€œpeople in China can put anything in the kernelâ€ routine then Iâ€™ll know heâ€™s not so good at looking at the complete picture.
The ideal answer involves the size of the project, how many developers are working on it (and what their backgrounds are), and most importantly â€” quality control. In short, thereâ€™s no way to tell the quality of a project simply by knowing that itâ€™s either open-source or proprietary. There are many examples of horribly insecure applications that came from both camps.
Whatâ€™s the difference between encoding, encryption, and hashing?
Encoding is designed to protect the integrity of data as it crosses networks and systems, i.e. to keep its original message upon arriving, and it isnâ€™t primarily a security function. It is easily reversible because the system for encoding is almost necessarily and by definition in wide use. Encryption is designed purely for confidentiality and is reversible only if you have the appropriate key/keys. With hashing the operation is one-way (non-reversible), and the output is of a fixed length that is usually much smaller than the input.
Who do you look up to within the field of Information Security? Why?
A standard question type. All weâ€™re looking for here is to see if they pay attention to the industry leaders, and to possibly glean some more insight into how they approach security. If they name a bunch of hackers/criminals thatâ€™ll tell you one thing, and if they name a few of the pioneers thatâ€™ll say another. If they donâ€™t know anyone in Security, wellâ€¦consider closely what position youâ€™re hiring them for. Hopefully itâ€™s a junior position.
Ok, now for some scary-advanced questions:
1. If Iâ€™m on my laptop, here inside my company, and I have just plugged in my network cable. How many packets must leave my NIC in order to complete a traceroute to twitter.com?
The key here is that they need to factor in all layers: Ethernet, IP, DNS, ICMP/UDP, etc. And they need to consider round-trip times. What youâ€™re looking for is a realization that this is the way to approach it, and an attempt to knock it out. A bad answer is the look of WTF on the fact of the interviewee.
2. How would you build the ultimate botnet?
Answers here can vary widely; you want to see them cover the basics: encryption, DNS rotation, the use of common protocols, obscuring the heartbeat, the mechanism for providing updates, etc. Again, poor answers are things like, â€œI donâ€™t make them; I stop them.â€
Bonus: Scenario Role-Play
For special situations you may want to do the ultimate interview question. This is a role-played scenario, where the candidate is a consultant and you control the environment. I had one of these during an interview and it was quite valuable.
So you tell them, for example, that theyâ€™ve been called in to help a client whoâ€™s received a call from their ISP stating that one or more computers on their network have been compromised. And itâ€™s their job to fix it. They are now at the client site and are free to talk to you as the client (interviewing them), or to ask you as the controller of the environment, e.g. â€œI sniff the external connection using tcpdump on port 80. Do I see any connections to IP 188.8.131.52?â€ And you can then say yes or no, etc.
From there they continue to troubleshooting/investigating until they solve the problem or you discontinue the exercise due to frustration or pity.
http://danielmiessler.com/blog/25-quest ... -interview
Nice share! :)
I read it all thanks :)
thanks :) very good share :
Add a Comment