四点金

四点金

We found out that in contrast to public knowledge, the Pre-Shared Key (PSK) authentication method in main mode of IKEv1 is susceptible to offline dictionary attacks. This requires only a single active Man-in-the-Middle attack. Thus, if low entropy passwords are used as PSKs, this can easily be broken.

This week at the USENIX Security conference, Dennis Felsch will present our research paper on IPsec attacks: The Dangers of Key Reuse: Practical Attacks on IPsec IKE. [alternative link to the paper]

In his blog post, Dennis showed how to attack the public key encryption based authentication methods of IKEv1 (PKE & RPKE) and how to use this attack against IKEv2 signature based authentication method. In this blog post, I will focus on another interesting finding regarding IKEv1 and the Pre-Shared Key authentication.

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.

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.

Pre-Shared Key authentication

As shown above, Pre-Shared Key authentication is one of three authentication methods in IKEv1. The authentication is based on the knowledge of a shared secret string. In reality, this is probably some sort of password.

The IKEv1 handshake for PSK authentication looks like the following (simplified version):

In the first two messages, the session identifier (inside HDR) and the cryptographic algorithms (proposals) are selected by initiator and responder.

In messages 3 and 4, they exchange ephemeral Diffie-Hellman shares and nonces. After that, they compute a key k by using their shared secret (PSK) in a PRF function (e.g. HMAC-SHA1) and the previously exchanged nonces. This key is used to derive additional keys (k_a, k_d, k_e). The key k_d is used to compute MAC_I over the session identifier and the shared diffie-hellman secret g^xy. Finally, the key k_e is used to encrypt ID_I (e.g. IPv4 address of the peer) and MAC_I.

Weaknesses of PSK authentication

It is well known that the aggressive mode of authentication in combination with PSK is insecure and vulnerable against off-line dictionary attacks, by simply eavesedropping the packets. For example, in strongSwan it is necessary to set the following configuration flag in order to use it:

charon.i_dont_care_about_security_and_use_aggressive_mode_psk=yes

For the main mode, we found a similar attack when doing some minor additional work. For that, the attacker needs to waits until a peer A (initiator) tries to connect to another peer B (responder). Then, the attacker acts as a man-in-the middle and behaves like the peer B would, but does not forward the packets to B.

From the picture above it should be clear that an attacker who acts as B can compute (g^xy) and receives the necessary public values session ID, n_I, n_R. However, the attacker does not know the PSK. In order to mount a dictionary attack against this value, he uses the nonces, and computes a candidate for k for every entry in the dictionary. It is necessary to make a key derivation for every k with the values of the session identifiers and shared Diffie-Hellmann secret the possible keys k_a, k_d and k_e. Then, the attacker uses k_e in order to decrypt the encrypted part of message 5. Due to ID_I often being an IP address plus some additional data of the initiator, the attacker can easily determine if the correct PSK has been found.

Who is affected?

This weakness exists in the IKEv1 standard (RFC 2409). Every software or hardware that is compliant to this standard is affected. Therefore, we encourage all vendors, companies, and developers to at least ensure that high-entropy Pre-Shared Keys are used in IKEv1 configurations.

In order to verify the attack, we tested the attack against strongSWAN 5.5.1.

Proof-of-Concept

We have implemented a PoC that runs a dictionary attack against a network capture (pcapng) of a IKEv1 main mode session. As input, it also requires the Diffie-Hellmann secret as described above. You can find the source code at github. We only tested the attack against strongSWAN 5.5.1. If you want to use the PoC against another implementation or session, you have to adjust the idHex value in main.py.

Responsible Disclosure

We reported our ﬁndings to the international CERT at July 6th, 2018. We were informed that they contacted over 250 parties about the weakness. The CVE ID for it is CVE-2018-5389 [cert entry].

Credits

On August 10th, 2018, we learned that this attack against IKEv1 main mode with PSKs was previously described by David McGrew in his blog post Great Cipher, But Where Did You Get That Key?. We would like to point out that neither we nor the USENIX reviewers nor the CERT were obviously aware of this.
On August 14th 2018, Graham Bartlett (Cisco) email us that he presented the weakness of PSK in IKEv2 in several public presentations and in his book.
On August 15th 2018, we were informed by Tamir Zegman that John Pliam described the attack on his web page in 1999.

FAQs

Do you have a name, logo, any merchandising for the attack?
No.
Have I been attacked?
We mentioned above that such an attack would require an active man-in-the-middle attack. In the logs this could look like a failed connection attempt or a session timed out. But this is a rather weak indication and no evidence for an attack.
What should I do?
If you do not have the option to switch to authentication with digital signatures, choose a Pre-Shared Key that resists dictionary attacks. If you want to achieve e.g. 128 bits of security, configure a PSK with at least 19 random ASCII characters. And do not use something that can be found in public databases.
Am I safe if I use PSKs with IKEv2?
No, interestingly the standard also mentions that IKEv2 does not prevent against off-line dictionary attacks.
Where can I learn more?
You can read the paper. [alternative link to the paper]
What else does the paper contain?
The paper contains a lot more details than this blogpost. It explains all authentication methods of IKEv1 and it gives message flow diagrams of the protocol. There, we describe a variant of the attack that uses the Bleichenbacher oracles to forge signatures to target IKEv2.

Try Variations on Your Passcode

Are you entirely sure you aren't misremembering your password? The first piece of advice we would give you is to ensure your passcode isn't being mixed up, or that you aren't forgetting a key piece of your passcode that happens to come at the end of the phrase. Plenty of us often forget about little tweaks to passwords we've added in order to ensure that our devices are as secure as possible. Here are some tips to making sure you're remembering every piece of your passcode:

Capital letters: If you're using a passcode phrase, you might've forgotten to add in any capital letters to your text. Make sure you remember to place the capital letters correctly as well; we've all forgotten the correct word or letter to capitalize in passcodes like this.
Numbers: Sometimes you forget about the number you added on your passcode a couple days ago. If your passphrase spells out "WaterInJuly382," you'll want to make sure you remember to enter the "382" part of the password. Don't be surprised if you accidentally forget to add the numbers onto your passcode. It happens to the best of us.
Special characters: Just like the capital letters, sometimes we add special characters into our passcodes to make them as complex as possible, only to forget the characters just hours later. Think back to decide whether you added an exclamation point, a dollar sign, or any other special character to your code in order to protect your data. It might make the difference between a lost passcode and saving your data.

Find My Mobile (Samsung Devices Only)

Are you using a Galaxy S9 or a Galaxy Note 8? You might be in luck: Samsung's own Find My Mobile tool features an additional feature not offered by Google's own Find My Device tool. Find My Mobile is similar to Find My Device or Find My Phone on iOS, but developed by Samsung specifically for their devices. For the most part, it does the same stuff you'd expect: Find My Mobile can locate your phone using GPS, make the device ring when you lose it in your couch cushions, and can even backup your data remotely using the web app offered by Samsung. More importantly, however, is the app's ability to unlock your device from your computer even if you've forgotten the passcode for the device.

There's a catch: if you haven't set up your Samsung account on your Galaxy S-device, you won't be able to do this. Like most of Samsung's tools, you need a Samsung account to log into the site and to unlock your device. Assuming you have set up your Samsung account—and haven't forgotten the passcode to that account—you should be able to unlock your device using the Find My Mobile web app here. All you need to do is sign in with your Samsung account, select the option to remotely unlock your device, and you'll be all set to go.

It's important to note that unlocking your device remotely does clear the biometric data off your device, so any fingerprints or iris scans you have saved on your device will have to be added back to your phone – small price to pay for saving your device's data in the long run.

As we mentioned, Google has a similar utility for all Android phones called "Find My Device," which only features the option to lock your device, not unlock it. If you've forgotten your passcode, all Find My Device will do is locate the device by GPS, re-lock the screen, and erase data; it won't be able to unlock the screen from the cloud.

Last Resort: Resetting Your Device

Unfortunately, thanks to the security enhancements added to Android 5.0 and above, most modern devices that aren't made by Samsung will have to be reset in order to bypass the password. Yes, this means you'll need to set your phone up again from scratch, re-downloading apps, music, and any other content you have saved on your mobile device. Being locked out of your device makes it difficult to back up any content on your phone, but if you already have some backup methods put in place, you can trigger them by plugging your phone. Both Google Drive backups (Pixel only) and Google Photos backups are often triggered by plugging your phone into a charger, so making sure your device is plugged in is ideal for guaranteeing that your software is saved. We recommend waiting until morning to reset your device if you're locked out; plenty of these backups happen overnight, including most SMS backups if you have an SMS backup app installed and running on your device.

Because you can't access the settings menu to factory reset your phone, you'll need to either use the hardware buttons on your phone to trigger a reset or use Google's Find My Device page in a web browser to reset the phone. Here's how to do each step:

If you're using Google's Find My Device page, load the URL here, sign into your Gmail account, and make sure your phone is selected. On the right side of the display, you'll see a Google Maps layout with a display showing the current location of your phone. On the left side of the display, you'll see a tab with three options: Play Sound, Lock, and Erase. Hit the Erase option to automatically trigger a device reset. Remember that your phone has to be powered on and connected to the internet in order to use this method.

Now, if you don't have access to the phone and can't use Find My Device to restore the phone over the web, you'll need to rely on the second method. To manually erase the device and reset the phone, you'll need to use the hardware buttons to load into your device's recovery system. This is accomplished a little differently on every phone, so your best option is to search for your phone model on Google with the keywords "boot into recovery." Some devices, like Samsung's lineup of phones, are fairly easy to boot into recovery with; you turn off the phone and press and hold a specific button combination to boot into recovery. Other phones, like Google's Pixel 2 XL, are much more finicky, requiring you to press and hold on one key and press and release another at the right time in order to boot into recovery. There are so many various methods for each Android phone, it's basically a requirement to search for the correct method for your phone to do this.

Once you've booted into recovery mode, use your device's volume up and volume down buttons to scroll through the list until you reach "Wipe Data/Factory Reset." Use the power button to select this option, then confirm your selection on the next display. Your phone will begin to reset; make sure the phone is charged enough to ensure it can last at least 30 minutes without dying. Once your phone has rebooted back to the menu screen, you can set up your device by logging back into the Google account you use for your phone. It is vitally important you use the same Google account you used on your phone prior to resetting. Android has a built-in security protocol known as Factory Reset Protection that requires a recently-reset phone to have the same Google account as previously used on the device in order to prevent a thief from immediately using the stolen phone. If you don't have the password for your Google account, you can reset it, but that means you won't be able to log into your phone for 24 hours after the reset.

Backup + Factory Reset

Probably the best combination of things to do does require you plan ahead, and set up a backup of your phone's data to the Google Cloud. This way, even if you have to reset the phone for whatever reason, a reasonably current set of your phone's data will be available, intact, and ready to get your phone back into action. I will walk you through how to set this up. You will need a Google account for this.

To set up backup, follow these steps.

Go to Settings on your phone.
Select System->Backup.
Select Google backup.
Select "Backup Now"

Your phone will now copy the critical data to your Google account.

Restoring from backup is simple. After you reset your phone and attach your Google account to the phone again, it will automatically restore your data from backup. Running a backup takes only a few minutes on a WiFi connection, or even less if you keep your phone regularly backed up – get into the habit of setting off a backup every night when you go to bed and you will always have a near-realtime backup of your phone.

(Want to backup more than just your phone? You can with one of these speedy 4-TB portable hard drives from Toshiba. You can back up all the computers in your household, and still have room for a thousand movies.)

Unlocking Your Phone with Speed

If you aren't having trouble getting into your phone, but you want to make sure your phone is secure while simultaneously unlocking your phone with some serious speed in order to make your day easier, we have some advice. There are plenty of options for unlocking your device, and they all help to make unlocking your phone easier and to prevent a situation where you forget the code for your phone.

Smart Lock

Smart Lock is one of our favorite tools on Android that is unavailable on other platforms. It makes it easy to make sure your phone is always secure, while simultaneously working to stay out of your way when you want access to your device. Basically, Smart Lock offers Android users several ways to unlock their phones when they're using it, while keeping it locked when it's not near them. To turn on smart lock, you'll need to open up your settings menu on your Android device and head into the Security submenu. Under "Device Security," you'll find an option for Smart Lock. Type in your passcode or password to enter Smart Lock, and you'll be greeted with (as of writing) five unique options for unlocking your phone. Let's break each of these down:

On-body detection: This setting allows you to unlock your device once before disabling the lock for as long as the phone is in your hand or on your person. Using your smartphone's array of sensors, the device tracks when your device is in use, so you can turn the display off but keep the phone unlocked while it's in your hand. When your phone realizes that it's been set down, your phone will automatically re-lock, requiring a password. This isn't the most secure method Smart Lock offers, but it is pretty cool.

Trusted places: Sure, it's one thing to keep your phone locked when you're out on the town, but what about when you're sitting in your apartment watching Netflix and you just want to be able to use your phone without constantly worrying about your password? Trusted places works to use the GPS in your phone to detect that you're in a secure location of your choosing, and automatically keeps your phone unlocked for you. As soon as you leave your location, your phone relocks, keeping things safe and secure for you and your device.

Trusted devices: This might be the best of the five Smart Lock options, because it's ideal for keeping your devices safe when you're nearby and keeping your phone locked when you've left. Do you own a smartwatch, a fitness tracker, a set of wireless headphones, or any other device that syncs over Bluetooth? Trusted devices might be the option for you, allowing you to keep your phone unlocked when your phone is paired with your gadgets. Smartwatches and fitness trackers are ideal for this, but it also helps you keep your phone unlocked when driving in your Bluetooth-equipped car, when running with Bluetooth headphones, or when paired with a set of Bluetooth speakers.

Trusted face: Plenty of phones have had a face unlock feature, though none of them are quite as secure as the FaceID method on the iPhone X. Still, if you want, you can enable Trusted Face on your device in order to allow your camera to automatically unlock your phone when it recognizes you. However, Trusted Faces is much more easily fooled than the above methods, especially since a photo of you—or even a lookalike—could unlock your phone without having to use any security. Use this one with caution.

Voice Match: Voice Match is a bit different than the other options on this list, because largely speaking, it's used to activate Google Assistant more than unlock your device. Here's the deal: turning on Voice Match allows you to access your Google Assistant every time you say "OK Google," even while the screen is off. Once you've enabled that ption, you have a second choice: "Unlock with Voice Match," which allows you to automatically unlock your phone when the sound of your voice saying "OK Google" matches the saved voice model on your device.

You can enable just one or all five of these, so don't worry if you like the idea of Trusted Devices but don't want to use On-Body Detection. If Smart Lock makes you feel like you can't properly keep your smartphone secured while enabling these settings, you don't need to worry. Every Android smartphone with Smart Lock enabled has the ability to lock the device manually, requiring a passcode or fingerprint in order to use the device properly. At the bottom of your lock screen is a small lock icon that allows you the choice of manually locking your phone. How you use it is actually a little different depending on your device; for example, Samsung devices have you press the icon to lock the app, but the Pixel phones have you press and hold the icon.

Once you've done this, your phone will give you a small notification alerting you that your device has been manually locked, and that the device will stay locked until you're ready to manually unlock with either your fingerprint (if you've turned this on) or your passcode. Manually locking your phone disables all smart locks, so even if you turn on a trusted Bluetooth device, you'll have to either input your passcode or password, or use your fingerprint to unlock the device if you have biometric security enabled. We'll talk more about fingerprints in the section below, and more specifically, how you can keep your biometric data from being used against you on upcoming versions of Android.

Smart Lock is one of those features that seems like a no-brainer, since it's so damn easy to setup and use to your benefit. That said, using Smart Lock obviously raises security concerns overall, since it does keep your phone unlocked more often. You'll want to play around with Smart Lock to find the right combination of security and ease of use for you. Maybe that means unlocking the device when it's attached to your car's Bluetooth and when you're at home, but keeping it secured at work and leaving on-body detection disabled. Whatever the right combination is for you will likely be a personal decision, but with five different modes of Smart Lock available, you have plenty of options and combinations to choose from.

Fingerprints

Almost every Android device in 2018 has a fingerprint sensor equipped on the body of the device, allowing you to easily access your content without having to go through the hassle of entering your passcode every time you use your phone. Fingerprints aren't a perfect unlocking method, but they're fast, secure, and can be equipped with up to four fingerprint entries on most phones. If you aren't using the fingerprint sensor on your device, you should enable it if only to create a backup option. Even if you prefer to unlock your phone by using an unlock method like a PIN, pattern, or password, fingerprints are perfect if you're ever in danger of accidentally locking the device without knowing the proper password.

If you aren't one to use fingerprints to unlock your phone, one step you could take to ensure you never forget your passcode is set the fingerprint on your phone to unlock with a finger that isn't your thumb or index finger. For example, try using your pinky finger or your ring finger as a way to program a fingerprint without making it obvious. You'll always have the option to use your fingerprint as a backup if you forget your code, but otherwise, you'll be good to go when it comes to always having a way to unlock your phone. You could also try using the fingerprint of someone you intensely trust, like a partner or a child, if only to keep a backup that doesn't happen to be with you all the time. This is especially good if you're worried about being forced to unlock your phone by law enforcement, a pressing matter that is becoming more prevalent all the time.

Finally, if you're still worried about logging your fingerprints on your Android device due to security concerns, the upcoming release of Android P has a security feature built-in that allows you to quickly disable fingerprint scanning if you find yourself at risk of being forced to unlock your device. Called "lockdown" in the settings menu, the option allows you to immediately disable both fingerprints and Smart Lock, just by using the option that appears within the power menu on the lock screen. It only disables those features for one lock, but if you're in a place where you're worried your biometric or smartwatch lock features might be used against you, it's a great option to feel more secure.

Notes and Reminders

If you're the type of person who likes to use a complex password on their phone and balks at the idea of using any of the smart unlock features we highlighted above, you might want to consider using the lock screen text display as a way to leave yourself helpful notes and tips to make remembering your password that much easier. Every Android device on the market today has support for placing a message on the lock screen, and you can display some pretty long messages. While most people use this as a way to label their phone (the example in Android is "Joe's Android"), you can also use it to set what amounts to old password hints from Windows and other desktop operating systems.

So, for example, if you've set your password as the name and birthdate of your daughter (ie., "elizabeth1217"), you could set the reminder on your lock screen as "ebbirth", for "elizabeth1217." This can be done for any password, even if it's a random phrase. "Candy90erring60Blinders," for example, could be hinted at on your lock screen with "Reese's, Jewelry, Sunlight." You'll still have to work to remember the numbers and the correct words that match up with the other content, but it can go a long way in helping you to remember what your password is without giving it away. Again, this is totally optional, a way for users to remember their long passwords without having to deal with giving it away or writing it down.

Password Managers

This final tip is for those among us who have a reputation for forgetting passwords and passcodes. If you're always worried about losing your password to your phone and getting locked out, you might want to try using a password manager like Lastpass or 1Password, which allows you to save all your passwords in one place with a single unlock, typically requiring a fairly long phrase in order to gain access to your passcodes. We recommend Lastpass for password manager beginners, because it's free and works with all your devices out of the box. We recommend writing the passcode down somewhere safe and secure in your house, then saving your phone's password inside of Lastpass for safekeeping. It might seem like an odd choice, and certainly won't speed up the unlocking process if you do manage to forget your password, but it's always good to have a backup unlock method to keep your phone's data safe.

***

Losing access to your phone is a nightmare. It's where all of your personal data, from bank account information to photos of your family and friends, lives and is kept safe. Being locked out of your data can feel like the end of the world, but luckily, it doesn't have to be. Whether you're worried about locking yourself of your account, or you've recently updated your phone's password and want to make sure you don't lose it, there are plenty of options to ensure you don't lose access. And even if you have, you aren't completely out of luck, thanks to the various options that exist for getting back into your account.

If you're looking for a way to unlock your phone faster, there's all sorts of opportunities to make sure your Android device is ready for you to login without having to enter your password every time. Biometric security has become fairly commonplace in the mobile arena, and likewise, Smart Lock on Android has made it easy to keep your device secure when it needs to be and unlocked when it doesn't. Overall, the security options on Android have become so plentiful that there's no reason not to keep some kind of security on your Android device. Just make sure you remember the password before you save the account information.

@EVERYTHING NT

Related word

四点金

You either landed on this blog post because

you are a huge fan of Hacktivity
you bought this badge around a year ago
you are just interested in hacker conference badge hacking.

or maybe all of the above. Whatever the reasons, this guide should be helpful for those who never had any real-life experience with these little gadgets.

But first things first, here is a list what you need for hacking the badge:

a computer with USB port and macOS, Linux or Windows. You can use other OS as well, but this guide covers these
USB mini cable to connect the badge to the computer
the Hacktivity badge from 2018

By default, this is how your badge looks like.

Let's get started

Luckily, you don't need any soldering skills for the first steps. Just connect the USB mini port to the bottom left connector on the badge, connect the other part of the USB cable to your computer, and within some seconds you will be able to see that the lights on your badge are blinking. So far so good.

Now, depending on which OS you use, you should choose your destiny here.

Linux

The best source of information about a new device being connected is

# dmesg

The tail of the output should look like

[267300.206966] usb 2-2.2: new full-speed USB device number 14 using uhci_hcd
[267300.326484] usb 2-2.2: New USB device found, idVendor=0403, idProduct=6001
[267300.326486] usb 2-2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[267300.326487] usb 2-2.2: Product: FT232R USB UART
[267300.326488] usb 2-2.2: Manufacturer: FTDI
[267300.326489] usb 2-2.2: SerialNumber: AC01U4XN
[267300.558684] usbcore: registered new interface driver usbserial_generic
[267300.558692] usbserial: USB Serial support registered for generic
[267300.639673] usbcore: registered new interface driver ftdi_sio
[267300.639684] usbserial: USB Serial support registered for FTDI USB Serial Device
[267300.639713] ftdi_sio 2-2.2:1.0: FTDI USB Serial Device converter detected
[267300.639741] usb 2-2.2: Detected FT232RL
[267300.643235] usb 2-2.2: FTDI USB Serial Device converter now attached to ttyUSB0

Dmesg is pretty kind to us, as it even notifies us that the device is now attached to ttyUSB0.

From now on, connecting to the device is exactly the same as it is in the macOS section, so please find the "Linux users, read it from here" section below.

macOS

There are multiple commands you can type into Terminal to get an idea about what you are looking at. One command is:

# ioreg -p IOUSB -w0 -l

With this command, you should get output similar to this:

+-o FT232R USB UART@14100000  <class AppleUSBDevice, id 0x100005465, registered, matched, active, busy 0 (712 ms), retain 20>
    |   {
    |     "sessionID" = 71217335583342
    |     "iManufacturer" = 1
    |     "bNumConfigurations" = 1
    |     "idProduct" = 24577
    |     "bcdDevice" = 1536
    |     "Bus Power Available" = 250
    |     "USB Address" = 2
    |     "bMaxPacketSize0" = 8
    |     "iProduct" = 2
    |     "iSerialNumber" = 3
    |     "bDeviceClass" = 0
    |     "Built-In" = No
    |     "locationID" = 336592896
    |     "bDeviceSubClass" = 0
    |     "bcdUSB" = 512
    |     "USB Product Name" = "FT232R USB UART"
    |     "PortNum" = 1
    |     "non-removable" = "no"
    |     "IOCFPlugInTypes" = {"9dc7b780-9ec0-11d4-a54f-000a27052861"="IOUSBFamily.kext/Contents/PlugIns/IOUSBLib.bundle"}
    |     "bDeviceProtocol" = 0
    |     "IOUserClientClass" = "IOUSBDeviceUserClientV2"
    |     "IOPowerManagement" = {"DevicePowerState"=0,"CurrentPowerState"=3,"CapabilityFlags"=65536,"MaxPowerState"=4,"DriverPowerState"=3}
    |     "kUSBCurrentConfiguration" = 1
    |     "Device Speed" = 1
    |     "USB Vendor Name" = "FTDI"
    |     "idVendor" = 1027
    |     "IOGeneralInterest" = "IOCommand is not serializable"
    |     "USB Serial Number" = "AC01U4XN"
    |     "IOClassNameOverride" = "IOUSBDevice"
    |   }

The most important information you get is the USB serial number - AC01U4XN in my case.
Another way to get this information is

# system_profiler SPUSBDataType

which will give back something similar to:

FT232R USB UART:

          Product ID: 0x6001
          Vendor ID: 0x0403  (Future Technology Devices International Limited)
          Version: 6.00
          Serial Number: AC01U4XN
          Speed: Up to 12 Mb/sec
          Manufacturer: FTDI
          Location ID: 0x14100000 / 2
          Current Available (mA): 500
          Current Required (mA): 90
          Extra Operating Current (mA): 0

The serial number you got is the same.

What you are trying to achieve here is to connect to the device, but in order to connect to it, you have to know where the device in the /dev folder is mapped to. A quick and dirty solution is to list all devices under /dev when the device is disconnected, once when it is connected, and diff the outputs. For example, the following should do the job:

ls -lha /dev/tty* > plugged.txt
ls -lha /dev/tty* > np.txt
vimdiff plugged.txt np.txt

The result should be obvious, /dev/tty.usbserial-AC01U4XN is the new device in case macOS. In the case of Linux, it was /dev/ttyUSB0.

Linux users, read it from here. macOS users, please continue reading

Now you can use either the built-in screen command or minicom to get data out from the badge. Usually, you need three information in order to communicate with a badge. Path on /dev (you already got that), speed in baud, and the async config parameters. Either you can guess the speed or you can Google that for the specific device. Standard baud rates include 110, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 38400, 57600, 115200, 128000 and 256000 bits per second. I usually found 1200, 9600 and 115200 a common choice, but that is just me.
Regarding the async config parameters, the default is that 8 bits are used, there is no parity bit, and 1 stop bit is used. The short abbreviation for this is 8n1. In the next example, you will use the screen command. By default, it uses 8n1, but it is called cs8 to confuse the beginners.

If you type:
# screen /dev/tty.usbserial-AC01U4XN 9600
or
# screen /dev/ttyUSB0 9600
and wait for minutes and nothing happens, it is because the badge already tried to communicate via the USB port, but no-one was listening there. Disconnect the badge from the computer, connect again, and type the screen command above to connect. If you are quick enough you can see that the amber LED will stop blinking and your screen command is greeted with some interesting information. By quick enough I mean ˜90 seconds, as it takes the device 1.5 minutes to boot the OS and the CTF app.

Windows

When you connect the device to Windows, you will be greeted with a pop-up.

Just click on the popup and you will see the COM port number the device is connected to:

In this case, it is connected to COM3. So let's fire up our favorite putty.exe, select Serial, choose COM3, add speed 9600, and you are ready to go!

You might check the end of the macOS section in case you can't see anything. Timing is everything.

The CTF

Welcome to the Hacktivity 2018 badge challenge!

This challenge consists of several tasks with one or more levels of
difficulty. They are all connected in some way or another to HW RE
and there's no competition, the whole purpose is to learn things.

Note: we recommend turning on local echo in your terminal!
Also, feel free to ask for hints at the Hackcenter!

Choose your destiny below:

  1. Visual HW debugging
  2. Reverse engineering
  3. RF hacking
  4. Crypto protection

Enter the number of the challenge you're interested in and press [

Excellent, now you are ready to hack this! In case you are lost in controlling the screen command, go to https://linuxize.com/post/how-to-use-linux-screen/.

I will not spoil any fun in giving out the challenge solutions here. It is still your task to find solutions for these.

But here is a catch. You can get a root shell on the device. And it is pretty straightforward. Just carefully remove the Omega shield from the badge. Now you see two jumpers; by default, these are connected together as UART1. As seen below.

But what happens if you move these jumpers to UART0? Guess what, you can get a root shell! This is what I call privilege escalation on the HW level :) But first, let's connect the Omega shield back. Also, for added fun, this new interface speaks on 115200 baud, so you should change your screen parameters to 115200. Also, the new interface has a different ID under /dev, but I am sure you can figure this out from now on.

If you connect to the device during boot time, you can see a lot of exciting debug information about the device. And after it boots, you just get a root prompt. Woohoo!

But what can you do with this root access? Well, for starters, how about running

# strings hello | less

From now on, you are on your own to hack this badge. Happy hacking.

Big thanks to Attila Marosi-Bauer and Hackerspace Budapest for developing this badge and the contests.

PS: In case you want to use the radio functionality of the badge, see below how you should solder the parts to it. By default, you can process slow speed radio frequency signals on GPIO19. But for higher transfer speeds, you should wire the RF module DATA OUT pin with the RX1 free together.

四点金

Odo Head Spa offered by Odo Beauty Care Limited

網頁

2020年8月28日星期五

Practical Dictionary Attack On IPsec IKE