4 ms·
The use of RC4 is odd as it's fairly broken[1]. Misconfiguration? [1] http://blog.cryptographyengineering.com/2013/03/attack-of-week-rc4-is-kind-of-broken-in.h
by casca 12y ago
The use of RC4 is odd as it's fairly broken[1]. Misconfiguration?
[1] http://blog.cryptographyengineering.com/2013/03/attack-of-week-rc4-is-kind-of-broken-in.html http://blog.cryptographyengineering.com/2013/03/attack-of-we...
- AlyssaRowan 12y agoMisconfiguration. All RC4 ciphersuites are explicitly forbidden by RFC, and considered a severe vuln by CVE. https://tools.ietf.org/html/rfc7465 https://tools.ietf.org/html/rfc7465
- jvehent 12y ago75% of alexa's top 1 million have RC4 enabled [1]. It will take a lot of evangelizing to finally get rid of it. [1] https://securitypitfalls.wordpress.com/2015/03/13/february-2015-scan-results/ https://securitypitfalls.wordpress.com/2015/03/13/february-2...
- AlyssaRowan 12y ago…how about a new twist on an old partial plaintext recovery attack that can actually steal passwords in the wild, given a cute name and a logo, being demonstrated in 11 days at Black Hat Asia 2015? I think that might help speed things along a bit. https://www.blackhat.com/asia-15/briefings.html#bar-mitzva-attack-breaking-ssl-with-13-year-old-rc4-weakness https://www.blackhat.com/asia-15/briefings.html#bar-mitzva-a... If you're managing a system, do what the RFC said: turn off RC4 on all the servers and clients. You were warned!
- mike_hearn 12y agoI wonder if this is/was the amazing crypto breakthrough known as BULLRUN, or at least very similar. It seems likely that if academic researchers are now able to extract partial plaintexts from RC4 with nothing more than passive eavesdropping, it's possible that GCHQ/NSA has gone all the way.
- AlyssaRowan 12y agoIt's kind of confusing. BULLRUN/EDGEHILL projects are umbrella cover terms: Secure Communities of Interest regarding general access to NSA/GCHQ (respectively) efforts to defeat network communication technologies such as TLS and IPsec, not particular individual cryptanalytic attacks, vulnerabilities, backdoors or techniques. I think you want the PICARESQUE ECI compartment, specifically (TS//SI-PIQ). NSA are said to have had a "cryptanalytic breakthrough" which "surprised" GCHQ some years ago. Specific operational details are currently undisclosed, but there have been references to PIQ (PICARESQUE) blades at locations of some TEMPORA full-take feeds processing the (72-hour) network intercept ring buffers in nearline and providing passive decrypts on-site to the backend via crypt attacks. They have only one-way access, and aren't active/QUANTUM (MoTS/MiTM) attacks, or PAWLEYS (key-stealing) attacks. The prevalence of RC4 within TLS (and other protocols) at the time, that it apparently directly provides plaintext decrypts, and RC4's relative weakness, suggest it as the most likely candidate for attack. So, no, don't use RC4! …not that I've had the opportunity to reverse any of these blades recently, you understand…
- sp332 12y agoThat's a very sudden change. A lot of sites started using RC4 recently because it's immune to BEAST and Lucky13.
- AlyssaRowan 12y agoReally: no. There is nothing "very sudden" about RC4 exhibiting biases indicating it is weaker than it should be: ask any cryptographer. The break that's about to be disclosed in March is simply a new practical twist on a weakness published more than 10 years ago! A lot of sites got bad advice. (One might wonder about whether all that advice was truly given in good faith. Maybe.) The real fix for BEAST and Lucky13 is, and always was, to use TLSv1.2 with AEADs like AES_GCM, or CHACHA20_POLY1305. So do that.
- yuhong 12y agoWhich this site does. They put RC4 at the bottom probably because it is faster than 3DES.
- AlyssaRowan 12y agoSo's NULL, but that doesn't mean you should use it.