[Bug 533352] Re: [LUCID] We need "limit" Upstart-ed ssh respawning

Fumihito YOSHIDA hito at kugutsu.org
Sat Mar 6 16:21:12 GMT 2010


** Description changed:

  ssh is now handling by upstart native jobs(with /etc/init/ssh.conf
  configs), and "respawn" stanza. This is great works. But this behavior
  is not familiar for security paranoid.
  
  Scenario:
-   - sshd is enougth to berief, but this is not perfect. In future, if we have got vuln for exploiting sshd, that can "randomly" type atacks (e.g.: buffer overflow, it is exploitable with probabilistic atacks, like brute force.).
-   - endless respawning is weaken for these "memory address brute force" atacks.
+   - sshd is enougth to berief, but this is not perfect. In future, if we have got vuln for exploiting sshd, that can "randomly" type atacks (e.g.: buffer overflow, it is exploitable with probabilistic atacks, like brute force.).
+   - endless respawning is weaken for these "memory address brute force" atacks.
  
- IMHO, when using "respawn" stanza, it needs something "limit" stanza (e.g.: respawn limit 60 30) or any other way ( e.g.: MAC by AppArmor). limitation by "limit" can mitigates(atack speed limitation) probabilistic atacks. This limitation provides potential over-limit DoS, but unlimited respawning is dangerous.
- # May be, we have to improvement upstart respawn stanza, like "respawn delay" feature...
+ IMHO, when using "respawn" stanza, it needs something "limit" stanza (e.g.: respawn limit 60 30)
+ or any other way ( e.g.: MAC by AppArmor). 
  
- ....Yes, this wish is not only ssh services. But ssh is most popular +
- internet accessible services.
+ limitation by "limit" can mitigates(atack speed limitation) probabilistic atacks.
+ This limitation provides potential over-limit DoS, but unlimited respawning is dangerous.
+ 
+ # May be, we have to improvement upstart respawn stanza, like "respawn delay" 
+ # feature...(see https://bugs.launchpad.net/upstart/+bug/252997)
+ 
+ ....Yes, this wish is not only ssh services. But ssh is most popular + internet accessible services.
+ In general cases, administrator use "ufw limit ssh" settings. Its not hazardous.

-- 
[LUCID] We need "limit" Upstart-ed ssh respawning
https://bugs.launchpad.net/bugs/533352
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