SafeUM
Home Blog Services Download Help About Recharge

Axarhöfði 14, 110 Reykjavik, Iceland

Iceland - 2015
SafeUM
Blog
Services
Download
Help
About
Recharge
Menu
Archive
TOP Security!
15 Oct 2014

POODLE bites: exploiting the SSL 3.0 fallback

There are details of a vulnerability in the design of SSL version 3.0. This vulnerability allows the plaintext of secure connections to be calculated by a network attacker. This issue was discovered in collaboration with Thai Duong and Krzysztof Kotowicz (also Googlers).

SSL 3.0 is nearly 15 years old, but support for it remains widespread. Most importantly, nearly all browsers support it and, in order to work around bugs in HTTPS servers, browsers will retry failed connections with older protocol versions, including SSL 3.0. Because a network attacker can cause connection failures, they can trigger the use of SSL 3.0 and then exploit this issue.

Disabling SSL 3.0 support, or CBC-mode ciphers with SSL 3.0, is sufficient to mitigate this issue, but presents significant compatibility problems, even today. Therefore the recommended response is to support TLS_FALLBACK_SCSV. This is a mechanism that solves the problems caused by retrying failed connections and thus prevents attackers from inducing browsers to use SSL 3.0. It also prevents downgrades from TLS 1.2 to 1.1 or 1.0 and so may help prevent future attacks.

Google Chrome and other servers have supported TLS_FALLBACK_SCSV since February and thus we have good evidence that it can be used without compatibility problems. Additionally, Google Chrome will begin testing changes today that disable the fallback to SSL 3.0. This change will break some sites and those sites will need to be updated quickly. In the coming months, Google hopes to remove support for SSL 3.0 completely from our client products. 

Poodle Attack  (Padding Oracle On Downgraded Legacy Encryption)

Poodle Attack allows a attacker to steal “secure” HTTP cookies, authorization tokens and other data from the victim. The bug lies in the obsolete SSL3.0 which is most commonly not used these days, however Incase of a failed connection caused by a network attacker the browsers with new protocols will also try older protocol version including SSL 3.0

To work with legacy servers, many TLS clients implement a downgrade dance, in a first handshake attempt, offer the highest protocol version supported by the client, if this handshake fails, retry with older protocol versions. Unlike proper protocol version negotiation (if the client offers TLS 1.2, the server may respond with, say, TLS 1.0), this downgrade can also be triggered by network glitches, or by active attackers. So if an attacker that controls the network between the client and the server interferes with any attempted handshake offering TLS 1.0 or later, Google said.

Tags:
POODLE SSL MITM information leaks
Source:
Google Blog
2647
Other NEWS
3 Jul 2020 safeum news imgage An encrypted messaging service has been infiltrated by police
4 May 2020 safeum news imgage Two-Factor Authentication ​What Is It and Why You Should Use It
12 Dec 2019 safeum news imgage Encryption is under threat - this is how it affects you
4 Nov 2019 safeum news imgage Should Big Decisions Be Based on Data or Your Intuition?
7 Jun 2018 safeum news imgage VPNFilter malware infecting 500,000 devices is worse than we thought
4 Jun 2018 safeum news imgage Hackers target Booking.com in criminal bid to steal hundreds of thousands from customers
1 Jun 2018 safeum news imgage Operator of World's Top Internet Hub Sues German Spy Agency
30 May 2018 safeum news imgage US says North Korea behind malware attacks
29 May 2018 safeum news imgage Facebook and Google targeted as first GDPR complaints filed
25 May 2018 safeum news imgage A new reason to not buy these cheap Android devices
24 May 2018 safeum news imgage Flaws in smart pet devices, apps could come back to bite owners
23 May 2018 safeum news imgage Google sued for 'clandestine tracking' of 4.4m UK iPhone users' browsing data
21 May 2018 safeum news imgage LocationSmart reportedly leaked phone location data onto the web
18 May 2018 safeum news imgage The SEC created its own scammy ICO to teach investors a lesson
17 May 2018 safeum news imgage Thieves suck millions out of Mexican banks in transfer heist
All news
SafeUM
Confidential Terms of Use Our technologies Company
Follow us
Download
SafeUM © Safe Universal Messenger

Axarhöfði 14,
110 Reykjavik, Iceland

Iceland - 2015