QUESTION 1

(a) There are two analysis techniques in reverse engineering for mobile apps, static and dynamic.

(i) Set apart these 2 techniques.

(ii) Name one tool for static analysis and one tool for dynamic analysis for a exacting mobile platform

(b) Think about reverse engineering an Android App.

(i) Depict a flowchart to show the different steps.

(ii) Model the total time taken to reverse engineer the app. Which step is more time consuming? Is it possible to have real time reverse engineering for mobile applications?

(iii) Remark the coding for the APK installation procedure in Annex 1.

(iv) What is Dalvik changeable? How does Dalvik byte code differ from Java byte code?

(e) The case in (b) relates to reverse engineering towards class hierarchy identification. The 2 others objectives in reverse engineering are encryption and ARM information. Illustrate the methods of ARM reverse engineering.

QUESTION 2

(a) In real meaning security is holistic. Describe your reasoning using appropriate instances.

(b) Clarify three methods to authenticate a user and give an example of a real world two-factor authentication.

(c) What is an Access Control List (record)?

(d) Briefly portray four methods how confidentiality can be ensured.

(e) Availability is an important security concept. Offer two ways how web masters can ensure maximum availability of their web applications.

(f) Describe what happen during a DNS Cache Poisoning attack.

QUESTION 3

(a) Briefly illustrate the most significant web threat for the following types of submissions:

(i) Military Institution

(ii) Civil Liberties website, White House website

(iii) Financial Institution

(b) Elucidate what a Turtle Shell Architecture is and give an instance.

(c) Briefly give explanation the principle of least privilege using an appropriate example.

(d) Think about the following usual query for user login in PHP:

$Sql="SELECT*FROMtbl_userWHEREusername='".$_POST[‘username]."'AND
Password'".$_POST[‘password']."'";
$result=mysql_query($sql);

Let's assume that an intruder injected x' OR ‘x'='x in the username field and x' OR ‘x'='x in the code word field.
Elucidate what happen when the form is processed.

(f) Let's presume a query in a product detail page is as follows:

$sql="SELECT*FROM product WHERE product_id='".$-GET[product-id]"'";
At the moment an intruder injects an SQL command in the URL of the page, the code is like this 10'; DROP TABLE product; # and the URL looks like this: http://xyz.com/product.php?id=10'; DROP TABLE product; #
At the moment the query becomes this:
SELECT * FROM product WHERE product_id='10'; DROP TABLE product; #';
You might be doubting what the meaning of hash "#" is. It simply tells the MYSQL server to ignore the rest of the query.
Clarify what happen when the URL is processed with the injection as shown above.

(f) Describe what a Cross Site Scripting attack is giving a suitable case in point.

(g) Alice wishes to transfer $100 to Bob using bank.com. The demand produced by Alice will look similar to the subsequent
POST http://bank.com/transfer.phpHTTP/1.1
...
...
...
Content-Length:19;
Acct=BOB&amount=100

However, Maria notices that the same web application will execute the same relocate using URL parameters as follows:
Get http://bank.com/transfer.php?acct=BOB&amount=100 HTTP/1.1

Maria now decides to exploit this web application vulnerability using Alice as her victim. Maria has to construct the URL which will transfer $100,000 from Alice's account to her explanation.\

(i) Put up the above URL for Maria at this time that her malicious appeal is generated; Maria must trick Alice into submitting the request. The most essential technique is to send Alice an HTML email containing the link and expect Alice to click on it.
Assuming Alice is authenticated with the application when she clicks the link, the transfer of $100,000 to Maria's account will occur. Though, Maria understands that if Alice clicks the link, then Alice will become aware of that a shift has occurred. Consequently, Maria decides to hide the attack in a zero-byte image.

(ii) Write down the code that Maria must send to Alice in the email making use of a zero-byte image.

(iii) Elucidate using an appropriate example how bank.com can prevent such security vulnerability.

QUESTION 4

(a) Discriminate between symmetric and public key encryption cryptographic systems and their modes of operation.

(b) Put in plain words what hash functions are and using a suitable example show how to calculate the hash on a string using MD5.

(c) Make clear what do you understand by the terms hash collision and rainbow tables giving an appropriate example for each. Also describe how they can be prevented.

(d) Write a 6-pass iterative and 17-pass recursive PHP function using sha1 and salt "saltandsugar" to hash password (key) "mynameisdon".

QUESTION 5

(a) When a website is being hosted on a shared web server, any session variable can be viewed by other users on the same server. The illustration below shows such a scenario where a "user password" is in a session variable.

The on top of code is not secure, as the password is stored in plain text in a session variable.
If ($_SESSION[‘passwqord']==$userpass) {

// do sensitive things here

}
Put in plain words how to make the above code secure.

(b) With reference to Question 2(g), elucidate how Maria can view the content of transfer.php, assuming the bank.com website is hosted on a shared server and Alice has an account on the latter.

(c) To ensure higher security, if an attacker gets hold of a session key, most likely it should be expired. Using a appropriate instance show how session key should be changed for each new request the user makes.

(d) List five obligatory security practices when handling uploaded files.

(e) Offer one validation and sanitizing filters.