oss-security - Re: User man Local Root Exploit/Linux Kernel setgid Directory Privilege Escalation/PAM Owner Check Weakness

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Date: Mon, 14 Dec 2015 21:14:29 +0000
From: halfdog <me@...fdog.net>
To: oss-security@...ts.openwall.com
Subject: Re: User man Local Root Exploit/Linux Kernel setgid
 Directory Privilege Escalation/PAM Owner Check Weakness

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Dag-Erling Smørgrav wrote:
> halfdog <me@...fdog.net> writes:
>> 
http://www.halfdog.net/Security/2015/MandbSymlinkLocalRootPrivilegeEscalation/
>> 
>> http://www.halfdog.net/Security/2015/SetgidDirectoryPrivilegeEscalation/
>
>> 
> And the PAM issue?

That's the most questionable. Should it be expected from the pam
libraries to refuse authentication, when the owner/group of
/etc/shadow is completely off? Of course, attacker with possibility to
modify ownership of a single file would also find numerous other
targets to work on, but should it be so easy?

But even when deciding to change behavior, e.g. forcing libpam checks
on shadow to be root/[somegroup] and 0640 mode, could that break other
existing systems, introduce new (availability) risks?

hd

- -- 
http://www.halfdog.net/
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