A the same time, the creativity of people who want to break a website is endless, so all bottlenecks should be well secured. In the first article I would like to describe and clarify some common methods of hacking one of the most vulnerable parts of a website — the forms. I will elaborate on how to use those methods and how to prevent attacks, as well as put some insight into basic security testing.
This method was really effective before frameworks become so trendy in PHP world. I put the question marks by purpose, because this example might be resolved in a couple of different ways. First will be the worst in my opinion and the most vulnerable for SQL Injection. Values are passed from the login form, right into the database query. In optimistic scenario, the user will put there his login and the password. What will happen in the worst scenario?
The form can be hacked by passing well prepared data. Our first attempt will login us as a first user from database. In most cases this will be an administrator account. The first quote mark can be also a semi, so probably it will take more than one attempt to achieve success. The quote is ended by the semicolon and two dashes, because everything what will be executed after the final comparison should be commented. This query will return the first user from database and probably log him into the application.
Web shells can be delivered through a number of Web application exploits or configuration weaknesses, including:. The tactics above can be combined regularly. For example, an exposed administration interface also requires a file download option, or another method of explanation mentioned above, for successful distribution. However, this is only a small number of Web shells used.
Find complete list of web shell here at github. Collection of PHP backdoor Web shells. WSO is a favorite hacker web shell because of its particularly powerful features. Once installed on a Web site, web hulls are notoriously difficult to remove, largely because hackers often place multiple copies of a web shell on one site in an attempt to retain access even if some of their programs malicious ones are removed.
A web shell is a type of malicious file that is uploaded to a web server. Potential infection methods include SQL injection or the inclusion of remote files through vulnerable Web applications. Web shells typically contain a Remote Access Tool RAT , or backdoor functionality, which allows attackers to retrieve information about the infected host and forward commands to the primary server through HTTP requests.
This module works when safe mode is disabled on the Web server. This shell is widely used in automated RFI payloads. To get access of your Web server, hackers sometimes installs a backdoor PHP web Shell designed to allow them to find the same entry after you have cleaned the site, fixed the security hole which allowed the hack and also to circumvent the measures to lock future hacker attempts that you could put in place to improve the security of the site.
A backdoor script can be called from a browser just like any other web page. Backdoors can be hard to find because they are usually hidden in files that are already part of the site or downloaded as new files with innocent names, most often placed in a directory with many files. There are a couple of ways of doing Web Shell Detection. One approach is to have an automated system look at the contents of newly uploaded or changed files and see if they match a known web shell, just as antivirus software does with other forms of malware.
You can use our WordPress security scanner here. Another way is to use pattern matching to look for code fragments down to the level of individual function calls that are commonly malicious, such as calls out to the system to manipulate files or open connections. Backdoors scripts often need to use non-legitimate PHP commands, so you can look for these commands in the files on your server.
There are search programs that you can use to search for text in files. The two described below are the ones you run from a command line prompt , and therefore without a GUI. I recommend creating a spreadsheet that enumerates all code that can be used to upload files in the application to keep track of the application hardening process. Click here for details. Stack Overflow for Teams — Collaborate and share knowledge with a private group.
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Viewed 1. Improve this question. Gui Imamura 8 8 silver badges 26 26 bronze badges. Fred Tanrikut Fred Tanrikut 9, 4 4 gold badges 15 15 silver badges 7 7 bronze badges. Add a comment. Active Oldest Votes. Improve this answer. See php. Is there a specific reason for not using CURL? Also, using an extension unnecessarily can widen the attack surface of your app. Google php curl cve — Pocketsand. Show 13 more comments. YanDatsiuk 1, 2 2 gold badges 16 16 silver badges 27 27 bronze badges.
This version uses curl library and I think is most "universal" so I give you my vote — Dayron Gallardo. You didn't site where you copied this code sample from: davidwalsh. Show 2 more comments. Dima L. To clarify: I think DimaL. Radon Show 1 more comment. Installing Guzzle Go to the command line in your project folder and type in the following command assuming you already have the package manager composer installed. Community Bot 1 1 1 silver badge.
Andreas Andreas 2, 21 21 silver badges 30 30 bronze badges. It would be useful to know what advantages this has over the native PHP solution already posted, and the cURL one too.
And why not use cURL in this case? It's simple: Guzzle has a straight-forward, easy, light-weight interface which abstracts all those "low-level cURL handling problems" away. Thanks, I know guzzle is popular, however there are use cases when composer causes grief e.
Andreas while you are right, this is a good example of more and more abstraction leading to less and less understanding of low-level technology thus leading to more and more devs not knowing what they are doing there anyway and not beeing able to debug even a simple request. Obviously, everyone using Guzzle should still be able to debug requests and also have a basic understanding of networking and how HTTP works.
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