Monday, November 2, 2015

Vulnerabilities in Voice Biometrics

The following vulnerabilities are found in voice biometrics:

Replay: The biggest concern is the replay attack. Hackers might attempt to gain unauthorized access to a voice authenticated system by playing back a pre-recorded voice sample from an authorized user. Need to implement proper anti-replay/ spoofing measures.

Voiceprint re-enrollment (Social Engineering): The malicious user claims to the contact center agent that they are unable to authenticate with their voice, and that their voiceprint needs to be re-enrolled. If the agent complies, a fraudster can be enrolled in the system and be provided with access to a legitimate account.

Brute Force attack: This attack consists of a fraudster calling the IVR or call center numerous times until their voice is mistakenly accepted by the voice biometric system as belonging to a legitimate account holder. Vulnerability testing conducted on deployed voice biometric systems indicates that the rate of a success of a brute force attack is between 0.1% and 0.5%.


Replay attacks-

Any voice identification solution needs to include measures to detect replay attacks.
 -Voice biometrics should be able to tell the differences between real and fake users
-Anti-spoofing is the key.
-Challenge Response Mechanism

Text-Prompted Authentication: In text-prompted mode users enroll by repeating a set keywords (digits, places, names, etc). Verification requires the user to repeat a randomly generated sequence of a subset of those keywords. This mitigates the above threat, as the fraudster will not have a recording of the legitimate account holder’s voice speaking the random passphrase.
Text-Dependent Authentication with A Passphrase: Rather than having a universal phrase that an attacker can easily gain knowledge of, users can enroll with their own secret phrase. Users are then responsible for keeping their phrase secret (and remembering it). The system does not prompt the user to speak the specific phrase. Instead it asks them simply to repeat their secret phrase, making it difficult for an attacker to know what set of words to record to execute a replay attack.

Voice re-enrollment-
An agent can verify that the caller has recently enrolled and has not been able to verify. A caller that requests a voice biometric re-enrollment that has successfully authenticated previously is most likely either a fraudster, or does not need to be re-enrolled.

Brute force-
Very similar to classic brute force attack: Block the caller after pre-determined unsuccessful login attempts. If there are three concurrent failed authentication attempts on a single account, that account can be locked to minimize the probability of a successful attack.

Monday, October 5, 2015

Voice Biometrics: Advantages and Disadvantages

Less prone to compromise: Contrary to PIN/ Passwords storages compromised and stolen and replayed, the voice prints can not be replayed. Thus a compromised voiceprint is unusable for account access.
Anti reversing: A voiceprint is a hashed string of numbers and characters that represent how a specific individual’s voice rates on the myriad of characteristics being measured Also, it’s not possible to reverse engineer it to recover someone’s voice.
Proactive detection of known fraudsters: Each time a fraudster speaks within an IVR or to a contact center agent, the fraudster leaves his/her voiceprint in the same way that our fingers leave fingerprints when we touch an object. This enables an organization to create and store voiceprints of known fraudsters.
Non guessable: A voice is unique to the individual. It can’t be guessed unlike PINs or passwords.
Cost effective: The cost of implementation is low because there is no special hardware required. A simple telephone or microphone is all that a user needs to authenticate using her voice. Other methods of biometric authentication like fingerprinting and retinal scans require special devices.
Ease of usability: Most important to the future of voice biometrics is that it is the only biometric that allows users to authenticate remotely.
Quick enrollment: It is quick to enroll in a voice authentication system. The user is asked to speak a certain set of words or phrases, or to speak for a certain length of time.
Fast: Authentication is very fast; it can be completed in 0.5 seconds.
Less storage size: Another advantage is that the storage size of the voiceprint is small.

Relatively low security: The biggest disadvantage is the replay attack. Hackers might attempt to gain unauthorized access to a voice authenticated system by playing back a pre-recorded voice sample from an authorized user. Need to implement proper anti-replay/ spoofing measures.

Low accurate: Person voice change, the difference in speaking instruments etc can affect the recognition. Compared to that other forms of biometrics such as retinal or fingerprint scans are more accurate and less prone to change.

Wednesday, September 16, 2015

For non-proxy aware clients

Monday, August 10, 2015

Implementing HSTS

Everyone know the what HSTS (HTTP Strict Transport Policy) does- It instructs the browsers to load a website over HTTPS no matter what. You cannot load a website on the http. When you hit a website, eg,, the server returns ‘Strict-Transport-Security’ Header that tells that now onwards the website must be loaded over https.
We know the issue related to redirecting a site from http to https, the 302/ 301 redirects the site to its secure scheme by loading the when user hits . The issue here is the response from the first request which loads on http can be modified and contents can be replaced with some phishing ones. Still a large no. of websites do this redirection, one classic example is American Express. When you try to access first time , it redirects you to :

The website first loads as http and then makes a 301 redirect and loads again over https. The below pic will make it clearer:

Now let’s examine the following website (Facebook). Try accessing and it loads on . But there’s a difference here, instead of making 301/ 302 redirect the Facebook site makes a 307 redirect which is an internal redirect:

The 307 instructs that the browser is not going to make the first request itself on http, instead it will make the first request over https. The browser has refused to make any connection on insecure protocol http. Let’s examine the response:

You can see the HSTS header in the response:

All the sites which need to be loaded over https by default must be submitted to site. This site is maintained by chrome and has a list of domains which needs to be loaded over https by default. That means, when the browser is shipped, your site will be a part of the list where https is by default.

Tuesday, July 7, 2015

Bluetooth security modes and supported versions

Security Mode
Versions supported
No Security. Device operates in promiscuous mode allowing any other Bluetooth device to connect it
v2.0 and earlier devices support it.

v2.1 and later devices support for backward compatibility. 
Service level enforced security. Security measures are established after the channel is established. Supports Authentication, Authorization and Encryption.
v2.0 and earlier devices support it.

v2.1 and later supports for backward compatibility .
Link level enforced security. Security measures are established before the channel is established. Supports authentication and encryption.
v2.0 and earlier devices support it.

but v2.1 and later devices support for backward compatibility. 
It is a service level enforced security mode in which security procedures are initiated after link setup. Uses SSP (Secure Sample Pairing)
Mandatory for communication between v2.1 and later BR/EDR devices.

Backward compatible with any of the other three Security Modes.

Thursday, June 11, 2015

Difference between Cross-site scripting and Cross-frame scripting

Often mistaken and confused with each other- Cross site scripting (XSS) and Cross frame scripting (XFS) Both seems to be very similar to each other, but they are not. Both are pole apart. One deals with malicious Javascript injection, other one is related to framing of a particular page under another page. The later one is more of a phising attack.
XSS: Injection issue. Forced malicious javascript code execution in browser.

XFS: Phishing-like attack. Where a legitimate looking page is iframed inside a malicious website.


XSS: Input validation, Output encoding

XFS: Frame-busting code, so that the page can't be framed inside other websites.

Tuesday, May 5, 2015

One more attack on SSL

After Heartbleed, POODLE, one more in this series: