A reverse shell is a shell session established on a connection that is initiated from a remote machine, not from the local host. Attackers who successfully exploit a remote command execution vulnerability can use a reverse shell to obtain an interactive shell session on the target machine and continue their attack.
A reverse shell also called a connect-back shell can also be the only way to gain remote shell access across a NAT or firewall. To establish a typical remote shell, a machine controlled by the attacker connects to a remote network host and requests a shell session — this is called a bind shell. But what if the remote host is not directly accessible, for example because it has no public IP or is protected by a firewall?
In this situation, a reverse shell might be used, where the target machine initiates an outgoing connection to a listening network host and a shell session is established. Reverse shells are often the only way to perform remote maintenance on hosts behind a NAT, so they have legitimate administrative uses. However, they can also be used by cybercriminals to execute operating system commands on hosts protected from incoming connections by a firewall or other network security systems.
For example, a piece of malware installed on a local workstation via a phishing email or a malicious website might initiate an outgoing connection to a command server and provide hackers with a reverse shell capability.
Firewalls mostly filter incoming traffic, so an outgoing connection to a listening server will often succeed.
When attempting to compromise a server, an attacker may try to exploit a command injection vulnerability on the server system. The injected code will often be a reverse shell script to provide a convenient command shell for further malicious activities. To start with, the attacker needs to start a listener process on their system to listen for reverse shell connections incoming to their IP address, for example On Linux, this can be as simple as one netcat command:.
This will start a netcat listener on port Now the attacker needs to manually or automatically execute code on the remote machine to connect to the listener.
Kali Linux also comes with a set of ready webshellsincluding reverse shells. Codes are typically one-liners to allow injection using a single command. As with bash, a perl interpreter should be available on most Linux servers, so a perl command might be another way to obtain a reverse shell:. Unless you are deliberately using reverse shells for remote administration, any reverse shell connections are likely to be malicious.
You can mitigate the risk by selectively hardening your system:. Regardless of the technicalities, once an attacker has a way of executing OS commands, the system should be considered compromised — so the best protection from reverse shells is to prevent exploitation in the first place. Shell scripts are typically executed by exploiting a code injection vulnerabilityoften followed by privilege escalation to obtain root privileges. Keep up with the latest web security content with weekly updates.
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The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Could someone explain in deep what is reverse shell about and in what cases are we supposed to use it?
It's a n insecure remote shell introduced by the target. That's the opposite of a "normal" remote shell, that is introduced by the source. In addition to the excellent answer by Kay, the answer to your question why is it called reverse shell is because it is called reverse shell as opposed to a bind shell. Bind shell - attacker's machine acts as a client and victim's machine acts as a server opening up a communication port on the victim and waiting for the client to connect to it and then issue commands that will be remotely with respect to the attacker executed on the victim's machine.
This would be only possible if the victim's machine has a public IP and is accessible over the internet disregarding all firewall etc. Now what if the victim's machine is NATed and hence not directly reachable?
One possible solution - So what if the victim's machine is not reachable. My attacker's machine is reachable. So let me open a server at my end and let the victim connect to me. This is what a reverse shell is. Reverse Shell - attacker's machine which has a public IP and is reachable over the internet acts as a server. It opens a communication channel on a port and waits for incoming connections. Victim's machine acts as a client and initiates a connection to the attacker's listening server.
This is exactly what is done by the following:. Reverse shell is getting the connection from the victim or target to your computer. You can think of, your computer attacker acts like a server and listens on port specified by him, now you make sure victim connects to you by sending syn packet depends on reverse shell implementation whether it is implemented using tcp or udp principals.
Now connection appears as if victim himself intending to connect us. Now in order to trick the victim you need to perform social engineering attacks or do dns spoofing and make sure your victim runs the program.Windows PowerShell is Microsoft's shell and scripting language. The information presented here is useful to IT administrators, software developers, software testers, and managers. Even the skeptical will be convinced that Windows PowerShell is a must-have tool.
Windows PowerShell is Microsoft's comprehensive next generation shell environment and scripting language. Consider Windows PowerShell as a dramatic upgrade to the old cmd.
BAT files. Users may ask why there is a new command shell, when Cmd. Windows PowerShell is an improvement over previous Microsoft command line scripting technologies--this means that Windows PowerShell is easier to use for both simple and complex tasks, and is surprisingly easy to learn. This section provides concrete examples and highlights a few of Windows PowerShell's features. First, notice that the shell in Windows PowerShell looks like a traditional Windows command prompt.
Using Windows PowerShell will quickly feel quite natural after a brief ramp-up period. This is the functional equivalent of the old cd change directory command. You may note that having to type "set-location" every time you change the current directory is too much typing; this is correct. Windows PowerShell has an extensive set of shortcut aliases you can use.
The set-location cmdlet is aliased to sl a shortened version of the full cmdlet nameand to cd the "old" way. This article uses the full version of cmdlet names for improved readability. This lists the contents in the current directory which start with "Pow". This article uses all lower-case.
Understanding Reverse Shells
The get-childitem cmdlet is aliased to both dir for Windows familiarity and ls for Unix usersand aliased to gci for ease of typing. Next, use the copy-item cmdlet to copy the Windows PowerShell directory, including all sub-directories, to a new directory named PSBackup:. Then immediately delete the newly created directory and all its contents using the remove-item cmdlet:.
The next command uses the get-content cmdlet to fetch the contents of file Hello. The get-content cmdlet is roughly equivalent to the type Windows or cat Unix commands.
Finish the mini-demo by using the sl alias to change the working directory to the root drive:. Now, if all there were to Windows PowerShell was performing common file system navigation and manipulation tasks using a new set of commands, there would be no point in reading further. A brief, one-paragraph introduction could lead to that incorrect assumption. However, Windows PowerShell has many advantages over many current shell environments. New technology is useless unless there is a way to quickly learn the technology.
Programmers call this process discoverability. Windows PowerShell was designed with excellent discoverability characteristics, making it much easier to learn. For example, you can get a list of all cmdlets simply by typing get-command at the Windows PowerShell prompt.
You can also get detailed information about a particular cmdlet by typing get-help followed by the cmdlet name. Extensive experience teaching Windows PowerShell to engineers and managers shows that most engineers can become adept at using Windows PowerShell with a single day of practice.
The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.
There are some conventions as for what website physical path to choose you can read about it in this SO question. Thats about it. In this case you can also ignore step 3. You might be able by this stage to browse to static content as html but not.
NET resources like aspx files. If by browsing to. NET files you get a message saying The page you are requesting cannot be served because of the extension configuration you can solve it with this SO question.
Learn more. How to configure IIS 7 for localhost website? Ask Question. Asked 3 years, 10 months ago. Active 3 years, 10 months ago. Viewed 28k times.
Hack the Box Write-Up: DEVEL (Without Metasploit)
I am new in Asp. I want to run application without visual studio. How to do this. Manish Tiwari Manish Tiwari 1, 5 5 gold badges 30 30 silver badges 54 54 bronze badges. Active Oldest Votes. Jaqen H'ghar Jaqen H'ghar I did according to this but when i run hostname on browser it runs IIS home page.Hi all, I recently came across the term "reverse shell" on internet, but have not succeeded finding a definition for this term.
If anyone knows what this is and how it differs from a "regular" local or remote command shell, could you please explain Basically it is when a machine connects to you instead of you connecting to it. For instance, you run netcat on your localmachine listening on port Then you run a command security exploit or some other timed application on the remote machine that causes it to connect to you on port giving you a remote shell. It is often used when you can't initiate a connection to a machine but it can initiate a connection to you firewall, etc.
This would be why firewalls which block everything coming in but allow everything going out are useless. Not useless, just not nearly as effective at protecting the internal network as they should be. Also, unless you have a proxy server and only allow the proxy server out on port 80, that would be my port of choice for a reverse shell.
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The result is trivial code execution on any IIS server that allows users to choose the file name of their uploaded attachment.
Getting Started with the IIS 7.0 PowerShell Snap-in
For the following example, assume we have a web application that allows users to upload image files to the server. To complicate things, lets also assume that the application checks the file content to ensure that the uploaded file is a valid image. To exploit this, we need to generate an ASP script that drops a Meterpreter payload and configure a msfconsole instance to handle the session. First we generate an ASP script that does a Meterpreter connect-back to the system running Metasploit:.
Let's say that I have only one public IP address to use. In the original scenario the public IP was mapped to the old machine, and all was fine. Now I have the need to "split" this public address between those two machines. What I want to do is, based on the host header, "redirect" or "rewrite" the request to the correct machine. I also tried the "Web Farm Framework" in combination with the previous two modules.
Short story: I can't make it work: all the requests are redirected to the "old" machine no matter what. Long story: I tried to make things as clean as possible. My cleanest attempt was making 2 server farms, the first with the new machine which is itself and the second with the old machine. In my rewrite rules, I put as first rule that anything that matches www1. In this scenario, everything gets routed to the old machine.
It's like the second rule takes priority if enabled, even if it's under the other one. If anyone has a solution to this, even a total different approach, you're welcome. I need to split that public IP on those two machines based on host header. What you are wanting to do is referred to as a "reverse proxy" and there are many options. Most "load balancers" are reverse proxies with a few niceties.
HAProxy is probably the most robust solution I am listing, but also has the most configuration options. You will need to have each site setup on the public server, or a complex ARR rule.
I find that having each site with its' own "site" in IIS tends to be straight forward. If you have say xml, or json services on the older server, you may want to migrate.
I am unsure of You have not really stated which you want to do it, I guessing as to split content to several servers.