25,000 Fortinet Devices Vulnerable To DUHK Attacks

Over 25,000 Fortinet devices used for vpn connections and accessible via the Internet are vulnerable to a new DUHK cryptographic attack, allowing attackers to decrypt passive vpn connections to read traffic.

DUHK stands for Do not Use Hard-coded Keys and was developed by Matthew Green , cryptographer and professor at Johns Hopkins University, in collaboration with Nadia Heninger and Shaanan Cohney. Vulnerability occurs with the ANSI X9.31 Random Number Generator (RNG) in combination with a hard-coded seed key. The ANSI X9.31 RNG is a more than 20 year old algorithm that was used to recently to generate cryptographic keys that are used to protect vpn connections and web sessions so that third parties can not intercept.

Through the DUHK attack, an attacker of vulnerable implementations can detect the secret encryption key, thus decrypting and reading traffic from vpn connections and web sessions. This may include sensitive information, such as company information, login information, credit card information, and other confidential content. The ANSI X9.31 RNG is used in many government-certified products. Until last year, ANSI X9.31 RNG was one of four number-generators approved by the United States for use in cryptographic modules. However, it has been removed from the list.

Network manufacturer Fortinet made use of this vulnerable number generator. It's about devices with FortiOS 4.x. All Fortinet vpn devices with FortiOS 4.3.0 to FortiOS 4.3.18 can be decrypted by a passive network attacker who can detect encrypted handshake traffic. Fortinet released FortiOS 4.3.19 last year to update the problem. According to Green, there are more than 25,000 vulnerable vpn devices on the Internet. The professor argues that it is a "conservative number", as only machines were counted that responded to the researchers' scans. The researchers have published a document with their findings ( pdf ) but will not disclose the attack code.

New Encryption Leak Threatens Web Servers And Mail Servers

A well-known cryptography professor has discovered a vulnerability in TLS encrypted connections allowing attackers to web and mail servers to attacks and eavesdropping. The vulnerability by Matthew Green " logjam "named and located in the Diffie-Hellman key exchange , a cryptographic algorithm that Internet protocols can establish an encrypted connection. It is essential for various protocols, including HTTPS, SSH, IPsec, SMTPS and protocols that rely on TLS.

Through the logjam attack attacker can, located between the victim and the Internet is vulnerable TLS connections to a 512-bit encryption downgrade. This allows an attacker to decrypt all the data on the encrypted connection and thus read and adjust. The vulnerability is similar to the FREAK-attack which was unveiled in March. Both vulnerabilities are caused by the US export policy in the early 1990s, making strong encryption could not be exported. Instead, if there is only "export-grade" encryption provided. The encryption keys were allowed in this case only 512 bits in size. However, the logjam-attack is focused on the exchange of keys via the Diffie-Hellman algorithm in place of the RSA-algorithm.

The attack affects all servers that Diffie-Hellman "export" encryption support. According to Green, all modern browsers and 8.4% of the 1 million most visited websites on the Internet vulnerable. The researchers experimented with attacking the most common primes 512-bit Diffie-Hellman used to exchange keys and were thus 80% of the servers with Diffie-Hellman "export" encryption downgrade. An intelligence could crack a 1024-bit prime and thus tapping 18% of encrypted connections from the 1 million most visited websites. Cracking a second prime number would make it possible to monitor 66% of VPN servers and 26% of the SSH servers.

Owners of a mail server or Web server are advised to disable the support of export encryption and generate a unique 2048-bit Diffie Hellman Group. Internet users should install the updates for their browsers as they become available. All suppliers are now working on an update. Finally get the advice to system administrators and developers to ensure that TLS libraries up-to-date and Diffie-Hellman Groups are refused less than 1024 bit.

New TLS / SSL Leak Hits Android And Apple Users

Researchers have discovered a new leak in TLS / SSL encrypted connections allowing attackers from Android and Apple users attacks. The problem that the name " FREAK Attack "has been, in some TLS / SSL servers and present clients, and allows an attacker located between the target and the Internet is the security of the TLS connection to a weak encryption can downgrade . Then this encryption can be attacked and content viewed from the protected traffic.

The vulnerability is caused by the US export policy in the early 1990s, making strong encryption could not be exported.Instead, there was only "export-grade" RSA encryption are supplied. The encryption keys were in this case only 512-bits wide.According cryptography professor Matthew Green was the 512-bit export-grade encryption weigh "dumb and dumber". "In theory was developed to ensure that the NSA communication could approach, while there could also be argued that the cryptography" "for commercial use." Good enough

According to Green led the need to support export-grade encryption to technical challenges. American servers were namely support both strong and weak encryption. The SSL developers were using a mechanism to set up a secure connection between two parties support the strongest encryption chooses which both parties. In theory, American users with American servers than strong encryption can use, while foreign clients with weak encryption are supported.

Most modern clients, such as browsers, would be to set up an encrypted connection is no export-grade encryption offer more.In addition, it was assumed that most servers nor export-grade encryption would offer more. Furthermore, an attacker in case there are still export-grade encryption for the encrypted compound was used must compute a 512-bit RSA key.

Researchers at Microsoft Research and INRIA IMDEA discovered that some modern TLS clients, including Apple's Secure Transport and OpenSSL, contain a vulnerability. Therefore they accept RSA export-grade encryption, even though they did not ask for this. According to Green, this bug has major consequences, since the attacker will connect to downgrade.However, the client in question need to be vulnerable, and the support server export-grade RSA. Contrary to what many people thought was export-grade RSA still in use. 36.7% of the 14 million websites investigated were found to support it.

"We thought that people were using it anymore," said Karthikeyan Bhargavan, a researcher from the French computer lab INRIA opposite the Washington Post . The team Bhargavan discovered the problem during testing of encryption systems.According to Nadia Heninger, a cryptographer at the University of Pennsylvania, we have here is actually a "zombie from the 1990s" to make. Heninger says that she can crack the export-grade encryption through the Amazon Web Services in 7 hours.

The vulnerability was already patched OpenSSL in January this year. Apple would now working on an update next week, and several internet parties are working to export-grade encryption to phase out. Google would now also have rolled out a patch among suppliers. However, it is up to these parties to the Android update to roll out among their users. Android users also get the advice to use a browser other than the one that comes standard.