Tuesday, December 22, 2015

Hot Links for the Juniper story

There's lots going on with the Juniper story. Here are some pointers to get you started:

  • Some Analysis of the Backdoored Backdoor
    Alas, while Juniper used Dual_EC_DRBG with the P-256 NIST curve and the point P specified in SP 800-90A in ScreenOS — the operating system running on NetScreen VPN gateways — they chose to use a different point Q and not the one supplied in the standard for P-256.


    However, apparently starting in August 2012 (release date according to release notes for 6.3.0r12), Juniper started shipping ScreenOS firmware images with a different point Q. Adam Caucill first noted this difference after HD Moore posted a diff of strings found in the SSG 500 6.2.0r14 and the 6.2.0r15 firmware. As we can deduce from their recent security advisory and the fact that they reverted back to the old value Q in the patched images, this was a change not authored by them.

  • On the Juniper backdoor
    The creepiest thing about CVE-2015-7756 is that there doesn't seem to be any unauthorized code. Indeed, what's changed in the modified versions is simply the value of the Q point. According to Ralf this point changed in 2012, presumably to a value that the hacker(s) generated themselves. This would likely have allowed them to passively decrypt and ScreenOS VPN sessions they were able to eavesdrop.
  • DUAL_EC Question of the Day
    People assumed that the NSA wanted a backdoored random number generator so they could look at other people's traffic, but of course a plausible answer is that a backdoored random number generator is even more useful for looking at your own traffic in an economical way.
  • CVE-2015-7755: Juniper ScreenOS Authentication Backdoor
    The argument to the strcmp call is (...), which is the backdoor password, and was presumably chosen so that it would be mistaken for one of the many other debug format strings in the code. This password allows an attacker to bypass authentication through SSH and Telnet. If you want to test this issue by hand, telnet or ssh to a Netscreen device, specify any username, and the backdoor password. If the device is vulnerable, you should receive an interactive shell with the highest privileges.
  • First Exploit Attempts For Juniper Backdoor Against Honeypot
    We are detecting numerous login attempts against our ssh honeypots using the ScreenOS backdoor password. Our honeypot doesn't emulate ScreenOS beyond the login banner, so we do not know what the attackers are up to, but some of the attacks appear to be "manual" in that we do see the attacker trying different commands.

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