Web Application:Authorization Issues

I have written one article that got published in Hakin9 Magazine's July Issue.
This article is about different kind of Access Control mechanisms and issues with them in Web Applications.
Access Control, as the name suggests, is the mechanism of determining privileges of different
users to access the contents of an application. It can also manage fine-grained read and write
permissions on the files owned by a particular user. In other words, access control decides who has the authorization to use files, manipulate their contents, or visit a website. In the case of web applications, access control mechanisms allow different users different levels of access to web pages and functions.
Want to read more? It can be found here or clicking on the list of articles in the right side of the blog.

Comments

File Upload through Null Byte Injection

Sometimes, during file upload we come across situation wherein there would be check on the file extension at the client side as well as server side too. If the application does allow only .jpeg extension to be uploaded, the client side java script checks for the extension of the file before passing the request. We all know that how easily this can be defeated. Some applications, checks for the extension at the server side also. That's not easy to bypass. However there are some ways with which it still can be bypassed. Most of server side scripts are written in high level languages such as Php, Java etc who still use some C/C++ libraries to read the file name and contents. That leads to the problem. In C/C++ a line ends with /00 or which is called Null Byte. So whenever the interpreter sees a null byte at the end of the a string, it stops reading thinking it has reached at the end of the string. This can be used for the bypass. It works for many servers, specially php servers. T...

'Information Leakage-Improper Error Handling' dropped

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jtool - an alternative to otool

jtool comes with a capability of running on Linux environment. Some ipa scanning tools are created to run on Linux environment where mac environment is not available. In such cases tools such as otool and class-dump-z will not work. So jtool can be an alternative to otool. For more information on jtool please refer to http://www.newosxbook.com/tools/jtool.html . It lists down various commands which have same output as otool or a equivalent. There are several commands mentioned in link. But for our customized requirements and basis checks I have listed down the below ones after running on many binaries. The outputs are similar or equivalent to otool and class-dump-z: Commands for checking PIE flag (ASLR) in jTool jtool -d -v -arch | grep stack · Automatic Reference Counting (ARC) protection: jtool -d -v -arch | grep _objc_release · To check if the devic...

Nilesh Kumar

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