** Visibility changed to: Public

** Description changed:

  (15:19:34) rlaager: Security Question: /usr/bin/at is currently permissioned 
"6755 daemon daemon". Doesn't that make it possible, if there's a bug in at, 
for a regular use to run at, which could be used to overwrite itself, leaving 
evil code for root to run later on? In other words, wouldn't 6555 be better?
  (15:29:36) infinity: rlaager: Can you file a bug?
  (15:29:56) infinity: rlaager: But yeah, potentially true of any non-root suid 
binary, I suppose.
  (15:30:15) ***infinity wonders how many of those we have...
  (15:30:59) rlaager: I think at is the only one (in a <= desktop install, 
which is what I have).
  (15:32:07) infinity: rlaager: The real bug could be that it should be 2755 
root:daemon instead.
  (15:32:33) rlaager: infinity: The changelog documents the intention to be 
suid daemon.
  (15:33:02) infinity: rlaager: Sure, but perhaps sgid would be enough.  Dunno. 
 Either way, bug report please. ;)
+ (15:35:54) rlaager: infinity: Should I subscribe the Ubuntu Security Team or 
not?
+ (15:36:06) infinity: Ahh, kay, so the changelog details why it needs to run 
as daemon (to signal atd), but it also claims it's installed 6555.
+ (15:36:19) infinity: So, it might just be a packaging error introduces later 
that made it 6755.
+ (15:36:25) infinity: I see no mention of the change.
+ (15:37:10) infinity: rlaager: If it's in previous releases as well, yeah.  
This would probably warrant an update.  It's not exactly a massive exposure 
window (or, possibly, not one at all, if at is bug-free), but it's a security 
bug nonetheless.
+ (15:38:11) infinity: The part where it does everything internally sgid, 
though, and only needs daemon to signal itself seems like something that cuold 
be fixed.
+ (15:38:14) ***infinity shrugs.
  
- ProblemType: Bug
- DistroRelease: Ubuntu 12.04
  Package: at 3.1.13-1ubuntu1 [modified: usr/bin/at usr/sbin/atd]
- ProcVersionSignature: Ubuntu 3.2.0-21.34-generic 3.2.13
- Uname: Linux 3.2.0-21-generic x86_64
- NonfreeKernelModules: nvidia
- ApportVersion: 2.0-0ubuntu4
- Architecture: amd64
- Date: Tue Apr  3 15:33:45 2012
- EcryptfsInUse: Yes
- InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta amd64 (20120330)
- ProcEnviron:
-  TERM=xterm
-  PATH=(custom, user)
-  LANG=en_US.UTF-8
-  SHELL=/bin/bash
- SourcePackage: at
- UpgradeStatus: No upgrade log present (probably fresh install)

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https://bugs.launchpad.net/bugs/972824

Title:
  /usr/bin/at should perhaps be permissioned 6555

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