Sometimes, an application vulnerability can be exploited in a way that allows an attacker to establish a reverse shell connection, which grants them interactive access to the system. Once the attacker gains this access to the system, they may conduct reconnaissance, lateral movement and try to escalate privileges. From there, they can steal sensitive data from the system or database, and install crypto miners. This difference is even more obvious in a microservice environment, given containers tend to be single, lightweight processes with rather rutinary conduct.
Falco detects this kind of abnormal behaviors in applications, containers and hosts. Sysdig Secure is the enterprise offering that not only detects abnormal behavior, but also takes response actions.
There, the server a ssh daemon is listening for the incoming request. Once received, it performs authentication and, if successful, an interactive connection is established. This is called the bind shelland it is easy to block from attacks.
Reverse shell tries to circumvent these protections by reversing the roles. It is the target machine that initiates the connection request to the user end. As firewalls usually have less restricted rules for outgoing traffic, instead of setting an interactive shell connection in the victim machine, an attacker could send a connection request to a shell listener on an attack machine with a public IP.
A common tool to set up such a shell listener is netcat. Observing a reverse shell running is a strong indicator that part of your system has been compromised. The earlier you detect such malicious behavior, the less damage can be caused.
Keep in mind that there are more advanced reverse shells which are more difficult to detect. We will also demonstrate how Sysdig Secure can help detect such advanced attack scenarios. Netcat can be used to both set up a shell listener and initiate reverse shell connections from the victim machine. The command above would launch a nc server listening on port On the victim side, the attacker would initiate the interactive shell connection with the following command:.There are two kinds of file operations in Lua namely implicit file descriptors and explicit file descriptors.
A sample of using implicit file descriptors is shown below. When you run the program, you will get an output of the first line of test. For our program, we got the following output. This was the first line of the statement in test.Python pour du Pentest Offensif #2 - Le Reverse Shell
Also the line "-- End of the test. In the above example, you can see how the implicit descriptors work with file system using the io. The above example uses io. The optional parameter can be any of the following. Reads from the current file position and returns a number if exists at the file position or returns nil.
We often use explicit file descriptor which allows us to manipulate multiple files at a time. These functions are quite similar to implicit file descriptors. The following example of the file version of the same implicit file descriptors example is shown below. All the modes of file open and params for read for external descriptors is same as implicit file descriptors. Sets the new file pointer with the updated file position from the beginning of the file.
The offsets are zero-based in this function. The offset is measured from the beginning of the file if the first argument is "set"; from the current position in the file if it's "cur"; or from the end of the file if it's "end".
The default argument values are "cur" and 0, so the current file position can be obtained by calling this function without arguments. An example to use the seek method is shown below. It offsets the cursor from the 25 positions prior to the end of file. The read function prints remainder of the file from seek position.Offensive Security offers a flexible training program to support enterprises and organizations of all sizes through the OffSec Flex Program. Offsec Flex Program.
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This allows you to easily add Metasploit exploits into any scripts you may create. Note: As of msfcli has been removed. One way to obtain similar functionality through msfconsole is by using the -x option.
The only real drawback of msfcli is that it is not supported quite as well as msfconsole and it can only handle one shell at a time, making it rather impractical for client-side attacks. Flexible training programs for organizations of all sizes. Using the MSFcli Interface. What is the MSFcli? Note: Although Zsh is often available, please be aware it isn't usually installed by default. Benefits of the MSFcli Interface Supports the launching of exploits and auxiliary modules Useful for specific tasks Good for learning Convenient to use when testing or developing a new exploit Good tool for one-off exploitation Excellent if you know exactly which exploit and options you need Wonderful for use in scripts and basic automation The only real drawback of msfcli is that it is not supported quite as well as msfconsole and it can only handle one shell at a time, making it rather impractical for client-side attacks.Lua is minimalistic, lightweight and embeddable scripting language.
The mailing list is open to get involved. Common use-cases for Lua includes scripting video games, extending applications with plugins and configs, wrapping some high-level business logic or just embedding into devices like TVs, cars, etc. For high performance tasks there is independent implementation using just-in-time-compiler available called LuaJIT. Block comments use the same style of delimiters as long strings; any number of equal signs can be added between the brackets to delimit a comment:.
A neat trick to comment out chunks of code is to surround it with --[[ and --]] :. This way, the sequence -- in the first line starts a single-line comment, just like the last line, and the print statement is not commented out. Taking this a step further, two blocks of code can be setup in such a way that if the first block is commented out the second won't be, and visa versa:.
To active the second chunk while disabling the first chunk, delete the leading - on the first line:. Another type in Lua is nil. The only value in the nil type is nil. It is a kind of non-value value.
Only false and nil evaluate as false, everything else, including 0 and the empty string evaluate as true. There are two types of for loop in Lua: a numeric for loop and a generic for loop.
The third expression in a numeric for loop is the step by which the loop will increment. This makes it easy to do reverse loops:. Also note that the loop variable is local to the for loop. It will not exist after the loop is over. Lua provides several built in iterators e.
How it works?Tool to generate a Linux kernel module for custom rules with Netfilter hooking. A sophisticated implementation of Unicode Bidirectional Algorithm. Cat's Eye Technologies' fork of the original public-domain Mini-Scheme implementation, miniscm. An implementation of advanced typographic tables of OpenType specification. Palantir is a Lua scriptable, portable, tiny reverse shell, using a human readable protocol written in C and Lua.
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Unix Command Shell, Reverse TCP (via Lua)
Free Trial. Products The Rapid7 Insight Cloud. Insight Products. DivvyCloud by Rapid7. Helpful Links. Penetration testing software for offensive security teams.IOT devices are notoriously insecure and this claim can be backed up with a laundry list of examples. With that in mind, I began to investigate the Mr. My hope was to build on previous work done by my colleague Douglas McKee fulmetalpackets and his Wemo Insight smart plug exploit.
Finding a similar attack vector absent in this product, I explored a unique avenue and was able to find another vulnerability. In this post I will explore my methodology and processes in detail. All Wemo devices have two ways of communicating with the Wemo App, remotely via the internet or locally directly to the Wemo App. Remote connectivity is only present when the remote access setting is enabled, which it is by default. However, if you are trying to control your Wemo devices locally, or the remote access setting is disabled, the Wemo app connects directly to the Wemo.
All my research is based on local device communication with the remote access setting turned off. In this case, I selected the Wemo application. With the capture running, I went through the Wemo app and initiated several standard commands to generate network traffic.
By doing this, I was able to view the communication between the coffee maker and the Wemo application. One of the unique characteristics about the app is that the user is able schedule the coffee maker to brew at a specified time. I made a few schedules and saved them. I began analyzing the network traffic between the phone application and the Mr.
Coffee machine. All transmissions between the two devices were issued in plaintext, meaning no encryption was used.
At this point I was able to see how the Wemo mobile application handled brewing schedules. Next, I wanted to see if the coffee maker performed any sort of validation of these schedules so I went back into the mobile application and disabled them all. I then copied the data and headers from the network capture and used the Linux Curl command to send the packet back to the coffee maker.
This indicated there was no validation of the source of brewing schedules; I further verified with the mobile application and the newly scheduled brew appeared. To understand how the schedules were stored on the Wemo coffee maker, I decided to physically disassemble it and look at the electronics inside.
Once disassembled, I saw there was a Wemo module connected to a larger PCB responsible for controlling the functions of the coffee maker. I then extracted the Wemo module from the coffee maker. This looked almost Identical to the Wemo module that was in the Wemo Insight device. After I obtained root access via the serial port on the Wemo device, I began to investigate the way in which the Wemo application is initiated from the underlying Linux Operating System.
It appeared the developers decided to take the easy route and used the Linux crontab file to schedule tasks instead of writing their own brew scheduling function.
Using the MSFcli Interface
The crontab entry was the same as the scheduled brew I sent via the Wemo application coffee-3 and executed as root. This was especially interesting; if I could add some sort of command to execute from the replayed UPNP packet, I could potentially execute my command as root over the network. As Lua is a scripting language, it was written in plaintext and not compiled like all the other Wemo executables. I followed the flow of execution until I noticed the rule passing parameters to a template for execution.
At this point, I knew it would be useless trying to inject commands directly into the rule and instead looked at modifying the template performing the execution. I went back to the Wemo mobile application network captures and started to dig around again. I found the application also sends the templates to the Wemo coffee maker. If I could figure out how to modify the template and still have the Wemo think it is valid, I could get arbitrary code execution.
Based on this, I knew it would be trivial to insert my own code; the only remaining challenge would be the MD5 hash included at the top of the template. As it turned out, that was hardly an obstacle. I created an MD5 hash of the base decoded Lua script and the base64 encoded script separately, simply to see if one or the other matched the hash that was being sent; however, neither matched the MD5 being sent in the template. I began to think the developers used some sort of HMAC or clever way to hash the template, which would have made it much harder to upload a malicious template.