Babak Sadeghiyan

Hossein Arabnezhad, Babak Sadeghiyan

In this paper, we study a block cipher based on cellular automata, proposed by Seredynski and Bouvry in \cite{semabo04} against \emph{plain-text avalanche criteria} and \emph{randomness} tests. Our experiments shows that Seredynski-Bouvry encryption scheme does not pass some NIST statistical tests by neighborhood radius less than three. It also showed that if the CA rule is selected carelessly, it weaken the security of scheme. Therefor, the selection of CA-rule as part of key can not be left to the user. Hence, cryptographic properties such as balancedness and non-linearity should be considered in the selection of CA-rules. This approach is more compliant with Kerckhoffs principle. So security should depend just on security of final data. We also improve Seredynski-Bouvry encryption scheme to satisfy strict avalanche criteria and NIST statistical test suite in about half number of iterations comparing to original scheme. This improvement is achieved by change in the definition of neighborhood.

Ehsan Edalat, Babak Sadeghiyan, Fatemeh Ghassemi

In this paper, we present a concolic execution technique for detecting SQL injection vulnerabilities in Android apps, with a new tool we called ConsiDroid. We extend the source code of apps with mocking technique, such that the execution of original source code is not affected. The extended source code can be treated as Java applications and may be executed by SPF with concolic execution. We automatically produce a DummyMain class out of static analysis such that the essential functions are called sequentially and, the events leading to vulnerable functions are triggered. We extend SPF with taint analysis in ConsiDroid. For making taint analysis possible, we introduce a new technique of symbolic mock classes in order to ease the propagation of tainted values in the code. An SQL injection vulnerability is detected through receiving a tainted value by a vulnerable function. Besides, ConsiDroid takes advantage of static analysis to adjust SPF in order to inspect only suspicious paths. To illustrate the applicability of ConsiDroid, we have inspected randomly selected 140 apps from F-Droid repository. From these apps, we found three apps vulnerable to SQL injection. To verify their vulnerability, we analyzed the apps manually based on ConsiDroid's reports by using Robolectric.