[SR-Users] Kamailio vulnerable to header smuggling possible due to bypass of remove_hf

jbrower at signalogic.com jbrower at signalogic.com
Wed Sep 2 19:48:48 CEST 2020

  Maxim is correct. *Anything* even remotely exploitable must be  
documented, fixed, and reported. Credibility with company security  
officers, CFOs -- even with the press if something bad should ever  
happen -- is crucial.

Whether there is an impacted standard is irrelevant. What standard  
ever covered RowHammer, Spectre, etc ?  If the exploit doesn't make  
sense because "they would have access to other private data anyway" is  
an assumption and therefore also irrelevant. Sophisticated hackers are  
great programmers (as are Kamailio programmers), they work 24/7 (as we  
do) -- who's to say how they might combine exploits in some way we  
cannot yet imagine.


Quoting Maxim Sobolev <sobomax at sippysoft.com>:

> Hey Daniel, Henning, Tao,
>    Thanks for commenting out. There are a lot of opinions for me to  
> address individually, so I will just clarify my opinion. The only  
> substantial difference I think is whether the issue at hand warrants  
> a security advisory to be issued by the Kamailio project or not. I  
> totally think that it does, but it looks like I am in the minority  
> here.
>    Why do I think this way? Well, the first argument is a bit  
> empirical. It is hard to generalize out of sample size 1, but in  
> like 90% engagements where I had to use SIP Proxy element and  
> integrate it with different SIP elements I ended up using "private  
> headers" for passing information between elements within that setup.  
> So the task of cleaning up those headers at the edge of the network  
> is very relevant at least to some users. It also matches Sandro's  
> assessment, which gives it at least some credibility.
>    Second, a more general one. Not only I have some experience in  
> software development field, but also I got a chance to participate  
> in much bigger and older open source projects (i.e. FreeBSD Project,  
> 400+ active developers, 1,000+ contributors) so I have seen how  
> security is dealt with properly in a mature open source project. You  
> guys might fancy the fact that Kamailio issued the last security  
> advisory in 2018 as a "code quality" indicator, but to me that shows  
> a total lack of proper security process.  With the code base of its  
> size, I'd expect at least several security issues of various  
> criticality being found per year. I frankly don't understand the  
> pushback I am getting. It almost looks like issuing such advisory is  
> viewed as harmful and damaging on project "spotless" reputation or  
> something. However in my view it would show respect to users and  
> understanding that many of those users might be using it in a way  
> that differs from its creators.
>    It might come as a surprise to some of you, but 95% of Kamailio  
> users are not reading this and those lists or following Sandro's  
> work in general. However, if there were a section "Security  
> Advisories" on kamailio.org[1] that would be the place to go. And  
> those users are often not individuals, but companies building their  
> products and solutions atop of Kamailio. 
>    Also properly issued security advisory helps package maintainers,  
> any linux distro of decent size has its own process to handle and  
> disseminate those among their own users to update package ASAP. But  
> if Kamailio chooses to not issue any it basically cuts itself out of  
> that process.
>    And last but not least, to the remark that I need to step in and  
> fix things, well I am hardly a person to do that. Too many projects  
> and too little time, however I also don't think I cannot voice my  
> opinion, or can I? By the way I know at least one person in the  
> Kamailio community that might be more fit as a "Kamailio Security  
> Officer": Olle E. Johansson.  Olle, what's your take on this? Does  
> this problem warrants security advisory?
>    -Max

[1] http://kamailio.org
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