Welcome back, my aspiring cyberwarriors!
Physical security is often an overlooked area of cybersecurity. If the attacker can physical gain access to your facility and your devices, GAME OVER! As a result, we have begun a new tutorial series and classes on physical security.
Introduction
Lock picking is a critical skill in a pentester’s toolkit, allowing them to bypass physical security measures non-destructively. One of the most precise and effective methods of lock picking is Single Pin Picking (SPP), where each pin inside the lock is manipulated individually. While basic SPP can be mastered quickly, advanced techniques require a deep understanding of lock mechanisms, precision, and a mastery of tactile feedback.
This guide explores advanced single-pin picking techniques for pentesters, focusing on detailed methods to overcome sophisticated lock systems in various real-world environments. Mastery of these techniques will not only help you gain access to restricted areas more effectively but will also strengthen your understanding of lock vulnerabilities, aiding in comprehensive physical security assessments.
Let’s do a quick review of lock-picking essentials
Finding the binding pins and using single pin picking to set them in the correct order
Binding Pin Recognition
The binding pin is the first pin that resists movement when tension is applied. Advanced locks often have security pins that bind irregularly. Identifying which pin is binding first and applying the right amount of upward pressure is the key to making progress. Use a systematic approach, probing each pin gently and identifying the one that feels solid or slightly stuck.
Advanced Techniques for Single Pin Picking
Mastery of advanced SPP relies heavily on refining your tactile sensitivity, understanding pin feedback, and manipulating difficult lock mechanisms with precision. Below are advanced techniques designed to overcome the challenges presented by security pins and complex locking systems.
The Importance of Tension Control
Tension is the foundation of successful lock picking. Without proper tension control, even the most experienced picker will fail to open complex locks. High-security locks often require extremely light tension to pick. These locks are designed to have tight tolerances and bind pins very easily. Applying too much tension may cause pins to set too tightly or bind in a way that provides no useful feedback. Mastering light tension involves balancing just enough pressure to keep the driver pins from dropping back down, while still allowing the pins to move freely.
Varying Tension
Complex locks with security pins often require variable tension techniques. After setting one or more pins, you may need to increase or decrease tension to manipulate subsequent pins without resetting the lock. This ability to “feel” the lock as you adjust tension dynamically is key to opening high-security systems.
Start with light tension to explore how the pins respond.
Increase tension slightly as some pins begin to bind, giving more control over individual pin movements.
Decrease tension occasionally if pins are over-set or to allow movement of stubborn pins.
The Jiggle Test
The jiggle test is a technique used in lockpicking to determine whether a pin has been properly set or over-set within the lock. It's a simple but effective way to gain feedback on the state of each pin as you manipulate them. This test involves gently applying a "jiggling" motion to the lockpick, allowing you to feel if a pin is loose, set correctly, or stuck.
How the Jiggle Test Works:
After applying tension, insert your lockpick into the keyway and begin manipulating the pins as you normally would, pressing each pin upwards to try to set it into the shear line. Once you believe a pin is set (or you’ve made progress with several pins), gently test each row of pins by jiggling the lockpick up and down while keeping light tension on the wrench. This subtle movement helps to test the state of each pin. Here's what you might feel:
Unset Pins: The pin goes up and down freely with consistent downward force from the spring. This means the pin hasn’t reached the shear line and isn’t set. This also means that this pin is not the current binding pin.
Under-Set Pins: If a pin moves freely with the initial touch, but as you progress the pick upward the pin feels tight and doesn’t move then you may have an under-set pin. Release some tension and continue to apply upward pressure until you feel a click.
Set Pins: When you initially lift the key pin will have no downward force from the spring, it will feel jiggly. As you continue to lift the key pin you encounter the driver pin at the shear line, which will move freely but you feel the downward force of the spring. As you slowly lower the pick you will also feel the driver pin catch on the shear line and the downward force of the spring will not follow as you lower the key pin. This pin doesn’t need further manipulation, and you can move on to the next one.
Over-Set Pins: You initially feel a void where the key pin should be resting. As you raise the pick and touch the pin it will feel overly tight and won’t move at all. This means the pin is over-set, lightly release tension and allow the key pin to drop.
Based on the feedback from the jiggle test, you can adjust your approach. If a pin feels loose, keep working on it. If it feels tight but the lock isn't opening, consider the possibility of an over-set pin and release some tension to reset the problematic pin.
Pin Identification and Feedback
In advanced SPP, the ability to identify and react to the feedback provided by each pin becomes critical. Pin stacks behave differently depending on whether the pin is a standard or security pin. Single pin picking mastery requires practice until you learn to interpret the tactile feedback from how the pin moves and how the tension wrench reacts.
Differentiating Standard Pins from Security Pins
Security pins give different feedback compared to standard pins. When a standard pin is lifted, it will feel smooth, and the tension wrench will rotate slightly with the pin’s movement. However, with security pins, the feedback can be deceptive.
Spool Pins: These have a narrowing in the middle, creating a false set where the plug rotates slightly, but the lock does not open.
Serrated Pins: These pins will give multiple clicks as you lift them, often making it difficult to tell when they are properly set.
Mushroom Pins: This pin gets its name from its shape, which resembles a mushroom with a tapering stem and a wide cap.
Feedback through the Tension Wrench
The tension wrench is more than just a tool to apply rotational force; it serves as your primary conduit for feedback from the lock’s plug. This indirect feedback is crucial for interpreting the behavior of individual pins in complex, high-security locks with security pins. Advanced pickers learn to read these subtle movements and use them to make informed decisions about how to proceed with picking.
As you apply rotational force with the tension wrench, the plug will resist movement until one or more pins are set. The moment a pin sets, the plug may move very slightly—often imperceptibly to the eye, but detectable through the tension wrench. This shift in the plug, however small, provides valuable feedback about the state of the lock.
For example, when a standard pin is set, the plug may "click" into place with a small but noticeable rotation. This gives the picker confirmation that the pin has reached its shear line. However, when security pins are involved, the feedback becomes more nuanced. Spool and mushroom pins, for instance, give the illusion that they are set, but subtle movements in the plug will indicate a false set and a pending need for counter-rotation.
Techniques for Manipulating Security Pins
Security pins are designed to resist picking by creating false feedback. They are typically found in higher-grade locks and, without the proper understanding, are a significant barrier for novice pickers. The following techniques help in overcoming these challenges.
Counter-Rotation for Spool Pins
Spool pins are among the most common security pins and are designed to produce false sets. When you apply tension, the spool pin will bind, and the plug will rotate slightly (indicating a false set). To identify the false set spool pin, you must release some tension from the tension wrench. Then use a hook pick to perform the jiggle test until you find the pin that causes the plug to counter-rotate (closely watch the black tick lines on the gif below to illustrate counter-rotation). Lightly let up on the tension wrench and push the spool pin until it sets. This process is delicate—releasing too much tension will reset the lock, while too little tension will not allow the counter-rotation.
Serrated Pin Manipulation
While spool pins use plug rotation to confuse you, serrated pins mimic the feeling of a set pin with "clicks". Instead of pin sets, these clicks are the pin catching on one of its serrations on the shear line. The key to mastering serrated pin is learning to distinguish the lighter and more dull feeling clicks of the serrations compared to a set click. When you find an under-set serrated pin, apply very light tension to the wrench and slowly lift the pin, feeling each serration click into place.
Manipulating Mushroom Pins
Mushroom pins are functionally spool pins but these pins are trickier. Due to their tapered stem they allow the plug to rotate further, thereby more closely mimicking the feel of a properly set pin than a spool pin. That being said, the process of setting mushroom pins is very similar to spool picking. The primary difference is that, due to the tapered stem, a mushroom pin only starts to counter-rotate when you have almost set it. (In comparison, the spool pin will almost immediately start to counter-rotate when you apply force.) With this in mind, understand you only need to lift the mushroom pin slightly when it begins to counter-rotate, or you risk oversetting it.
Lock picking, while a valuable skill for pentesters, also comes with ethical and legal responsibilities. Always ensure that you have proper authorization before picking any locks. Unauthorized lock picking can be illegal in many jurisdictions and could lead to legal consequences, even if done in the name of security testing.
Always operate within the guidelines of your contract, and make sure the client understands the scope of your physical security testing, including any lock-picking activities.
Conclusion
Advanced single pin picking is a crucial skill for pentesters looking to improve their ability to bypass physical security systems. By mastering tension control, pin feedback interpretation, and handling high-security locks, you can increase your efficiency and success in the field. Continuous practice on a variety of locks, under different environmental conditions, will enhance your skills and prepare you for real-world pentesting challenges.
For more on physical security for hackers/pentesters, attend our upcoming Physical Security trainings.