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Yahoo! CAPTCHA Cracked

A CAPTCHA is a type of challenge-response test used in computing to determine whether the user is human. The process involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade. Because computers are unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human. A common type of CAPTCHA requires that the user type the letters of a distorted image, sometimes with the addition of an obscured sequence of letters or digits that appears on the screen.

One of the strongest and most difficult CAPTCHAs to crack is used by Yahoo which ulilizes a mix of blended alpha numeric characters as show below.

Yahoo CAPTCHA

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Network Security Risk Assessment

In this article, I will introduce you to some well known tools which security analysts use for Network Security Risk assessment, to know more about the layout of the network they are trying to test and also gather intelligence about that company, which the security analyst can use later on to conduct further tests and poke it for its weak points. The more information we can obtain, the more we can advice our client company of any potential problem areas and provide a better Network Security Risk Assessment. This whole process is called footprinting.

Footprinting:(Definition from Wikipedia)

Footprinting is the technique of gathering information about computer systems and the entities they belong to. This is done by employing various computer security techniques, as Ping Sweeps, TCP Scans, UDP Scans, OS Identification, Network Enumeration, Registrar Queries, Organizational Queries, Domain Queries, Network Queries, POC Queries and DNS Interrogation

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TIBCO Rendezvous RVD Daemon Remote Memory Leak DoS

The TIBCO Rendezvous RVD daemon is vulnerable to a memory leak, which when remotely triggered, prevents any further RV communication until the daemon is manually restarted.

Vulnerability Type / Importance: Remote DoS / High
Workaround: There are no known workarounds for this vulnerability

The RV daemon (RVD) within TIBCO’s Rendezvous messaging product is responsible for the communication of messages between RV-enabled applications. The vulnerability exists as the result of an error in the code that parses information within one of the headers in a TIBCO proprietary network protocol packet.
Technical Details:
Within a Rendezvous “wire format” TCP packet, the first four bytes represent the number of bytes of data to expect within the packet, for example:
“0000007c” //total length of data in packet
“9955eeaa” // “magic” number
“06” // number of following bytes including null
“6d7479706500” //the text “mtype”
…etc

In the above example the number of data bytes in the packet is “0x7c”, or 124 bytes. If this value is set to zero in a packet sent to the RVD daemon then it stops responding to all subsequent communication. This appears to result from a memory leak, which continues to attempt to allocate memory. Eventually, operating system alert messages start to appear, warning that the virtual memory in the underlying operating system is running low.

http://www.youtube.com/watch?v=1hdsxUmVTBg

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Dirty Business: What Security and Pen Testers need to know to get the job done

This article is part # 3 in the series on Penetration Testing. The first in this series talks about Penetration testing as a profession and a general introduction. The second introduces you to some critical keywords and security tips you need to be aware of before proceeding through the rest of this series.

When you are performing the role of a security/pen tester, sometimes just having the right tools and skills is not enough. Either they are not enough or there are easier ways to get the management to understand how easy it is for someone to walk in and walk out with the keys to their “fort”.

One of the first things I want to share with you is what my Professor of a Security Class I took while I was an Undergrad at Florida Tech shared with us. So, he was performing a penetration test at a company and he was negotiating the price for which he is willing to perform the pen test of the company’s network. Apparantly, the company was driving a hard bargain. Finally, it reached an ultimatum situation and so the company asks… “why should we pay you so many X dollars more? Are you that Good?” or something on those lines. So my professor excuses himself from the meeting room on the pretext of using the rest room. He walks around the floor on which the meeting was set up. Here is what he finds. He finds passwords on Employees monitors, including in front of an employee who had an “Emergency Response Team” sign sitting outside his cube. As he is walking past he sees the Project Manager’s laptop bag with disks and flash drives in it, sitting outside near the receptionist or an employee’s desk. He just informs the lady that he was told to bring the bag inside, takes out the flash drive. He logs into one of the terminals, grabs some credentials stored on the flash drive, makes printouts of some confidential documents and brings it back to the meeting room, all within a time frame of around 5-10 minutes. No one asked any questions. My professor got the price he asked for and more and the company had an excellent pen test analysis done.

So what is the moral of this story: No matter how strong your filters are set or firewall configured. You must always take caution against the insider attack. You are only as strong as your weakest link. In this business, sometimes, we need to employ tactics such as social engineering amongst others to get our job done. In this article, I will talk about some of these tactics.

1. Using a Keylogger:  Keystroke logging (often called keylogging) is a diagnostic used in software development that captures the user’s keystrokes. It can be useful to determine sources of error in computer systems and is sometimes used to measure employee productivity on certain clerical tasks. Such systems are also highly useful for law enforcement and espionage—for instance, providing a means to obtain passwords or encryption keys and thus bypassing other security measures. A simple google search on download keyloggers gives you plenty of results. You might want to use a professional keylogger tool such as KeyKatcher or KeyGhost. While you are performing a security test on a system, keyloggers can be a helpful tool. However, please make sure that you have permission from the company to do something like this.

2. The ability to pick locks: Okay, this is one skill I don’t have too but if you are performing the role of a pen tester, remember that if something was stolen or picked from the company, it rather be you than some attacker. When performing a test, know the kinds of locks used by the company to secure its prime assets such as server rooms etc. While most companies these days are using card access, you might be in luck if they are using the traditional lock. An excellent paper highlighting the need for physical security is the “MIT Guide to Lock Picking” by an author who calls himself Ted the Tool. If you are going in this direction, contact your nearest law enforcement agency, fill out the necessary forms and get certified. The ability to pick the lock of a server room could be a valuable asset while performing a security test at a company. Again, please make sure you have permission from the company to do something like this.

Related Articles:

1. Introduction to Ethical Hacking and Penetration Testing

2. Important Computer Security Definitions and Terminologies

Introduction to Ethical Hacking and Penetration Testing

An Introduction to Ethical hacking through the eyes of a pen tester and hopefully helps anyone reading this blog on how to protect and secure a network by understanding how a Hacker operates and understanding their tools and methodologies.

Why would I want to publish such a series of articles; because, I did not want to be part of the problem anymore. The need to know and understand Computer Security has passed the realm of just security professionals. The web is an ugly place out there with hackers and crackers lurking at every corner selling their Trojans and the rest of their goods in the malicious code dept, trying to install Botnets and seeking to profit from your mistakes or rather lack of security awareness.
Every other day, you see articles on the newspaper and on the web on identity theft or credit card numbers being stolen from compromised database servers. The need for security professions who know networks and understand how Hackers operate is growing every day which companies utilizing such security professionals to test and break into their network before the bad guys do and patch up their security infrastructure. It is here that we, the “security tester” or “penetration tester” come in.

So what will you learn in this series on Penetration Testing?
I will try to offer you a structured approach to security and penetration testing. I will also try to explain in-depth some of the tools which hackers typically use. Remember you are trying to be the Ethical hacker and you need to know how to use and implement the tools of the trade.

A network is only as secure as its weakest link. You are trying to discover vulnerabilities within a network and find that weak link before the bad guys.

Disclaimer: You will learn about some tools and methodologies which are not meant to be used for Hacking purposes. Hacking or compromising a computer or a network is illegal in many parts of the world. Please use them to further understand how computer security works.  If you are trying to take up the role as a penetration tester for a company, make sure you have a contract signed with the client and what you can and cannot do clearly defined. Also, make sure you read your ISP’s contract and their acceptable use policy defining any scanning software such as port scanners. Anytime you run something that denies a user access to a system or a network resource is illegal.