Re: COSEINC Linux Advisory #1: Linux Kernel Parent Process Death Signal Vulnerability

On Wed, 15 Aug 2007, Wojciech Purczynski wrote:

Sending a signal to privileged process is a privilege itself.

Sure. But once control was transferred to some other code that we have no
control over, we have no more control over when the signal is sent. We just
can't send that signal at arbitrary moment. If you as an attacker can create
arbitrary setuid root binary in the system, this game is not worth anymore,
since you already won.

Under some
circumstances this may lead to other consequences. For example I was able
to code local root exploit using some very common suid binary, although
its usage is somewhat limited.

Again, if an attacker can create arbitrary setuid root binary in the system,
the latter is already broken. And if the setuid root binary allows arbitrary
code execution on getting some signal, it is vulnerable itself. Unexpected
signals can be generated at any time by terminals, init, various system
daemons, non-blocking i/o for files open before exec(), alarms, failed pageins,
etc. If the program (not necessarily setuid/setgid) can't properly handle those
situations, it is broken by design. Signals are not something we can trust.

Sincerely Your, Dan.

Relevant Pages

  • Re: Forth is broken by culture?
    ... least in our industry, it simply isn't possible to completely define ... which feeds a switch, aggregating multiple audio and control streams, ... digital signals flying around. ... This is a quirk in the sense that a user's expectation about how the ...
  • Re: Intermittent operation of 3 appliance modules AM486
    ... Plugging it into a Plug-In Noise filter did the trick. ... Christmas lights in season and just a couple of other lights during ... I am having fits with it because of seemingly random control ... signals are being transmitted properly. ...
  • Re: Entropy sources under WinXP
    ... Andy incurs the foolish face per the outlet? ... reportedly as Talal tears, you can hand the lifestyle much more ... Aneyd never signals until Ismat disposes the ... it gasps a control too ultimate near her different wood. ...
  • Re: Justify Upgrade from X-10 to Z-Wave?
    ... chair to operate room lighting or to turn-off lights in another room. ... but my experience is that a well installed X10 ... The XTB-IIR booms out strong signals to the ... control common area lighting in my condo building, ...
  • Re: Theory of beliefs, belief fields
    ... particular drug while turning all drug users into schizos (theory of side ... language requires fine control by the brain of several muscles, ... would be a combination between high physical sensitivity and weak direct ... base or essential character for very string signals. ...