oss-sec mailing list archives
Re: Healing the bash fork
From: "Stuart D. Gathman" <stuart () gathman org>
Date: Tue, 30 Sep 2014 19:40:07 -0400 (EDT)
On Tue, 30 Sep 2014, David A. Wheeler wrote:
Finally: *PLEASE* let me know if you have any good ideas on how to find vulnerabilities like this ahead-of-time. My article "How to Prevent the Next Hearbleed" (http://www.dwheeler.com/essays/heartbleed.html) lists a number of ways that Heartbleed-like vulnerabilities could have been detected ahead-of-time, in ways that are general enough to be useful. I'd like to do the same with Shellshock, so we can quickly eliminate a whole class of problems.
I don't know if this can be made efficient enought to be practical, but imagine a virtual machine where every byte of memory is tagged with the security domain. When a byte is copied, the tag is copied also. (It is not possible in general to distinguish copies from writes, but at least when copying between domains via system calls, this is detectable.) Then, when a privileged program is running, its memory can be scanned for data from a lower privilege domain.
I think this is optimizable, since most memory will have the same tag, and can be managed via virtual memory paging. Update on write logic will create a more detailed map for "hot" pages.
Caveat: someone probably already did this, and I just never heard of it.
Current thread:
- Re: Healing the bash fork, (continued)
- Re: Healing the bash fork Ed Prevost (Sep 30)
- Re: Healing the bash fork Rich Felker (Sep 30)
- Re: Healing the bash fork Michal Zalewski (Sep 30)
- Re: Healing the bash fork Simon McVittie (Sep 30)
- Re: Healing the bash fork Mark R Bannister (Sep 30)
- Re: Healing the bash fork Tavis Ormandy (Sep 30)
- Re: Healing the bash fork Ed Prevost (Sep 30)
- Re: Healing the bash fork Zach Wikholm (Sep 30)
- Re: Healing the bash fork David A. Wheeler (Sep 30)
- Re: Healing the bash fork Michal Zalewski (Sep 30)
- Re: Healing the bash fork Stuart D. Gathman (Sep 30)
- Re: Healing the bash fork Ed Prevost (Sep 30)
- Re: Healing the bash fork Martin Carpenter (Sep 30)