oss-security - Insecure pid directory permissions for postfix on Debian / Ubuntu

Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers

[<prev] [next>] [day] [month] [year] [list]

Date: Fri, 18 Sep 2009 14:25:16 -0500
From: Jamie Strandboge <jamie@...onical.com>
To: oss-security@...ts.openwall.com
Cc: coley@...us.mitre.org
Subject: Insecure pid directory permissions for postfix on Debian / Ubuntu

Wietse Venema discovered that Debian and Ubuntu set the permissions of
/var/spool/postfix/pid to be postfix:root 0755. This allows the postfix
user to manipulate pid files and overwrite arbitrary files via symlink
attacks. Arbitrary file overwrites are somewhat mitigated when using
chroot, which is the default on Debian and Ubuntu.

Currently supported versions of Debian and Ubuntu that are affected are
(earlier versions are likely affected, but not checked):
Debian: 4.0 (Etch) and later
Ubuntu: 6.06 LTS (Dapper) and later

The patch is attached. This is CVE-2009-2939.

Jamie

-- 
Jamie Strandboge             | http://www.canonical.com

diff -u postfix-2.5.5/debian/postfix.postinst postfix-2.5.5/debian/postfix.postinst
--- postfix-2.5.5/debian/postfix.postinst
+++ postfix-2.5.5/debian/postfix.postinst
@@ -211,9 +211,8 @@
     fi
 fi
 
-for dir in pid public; do
-    makedir ${dir} postfix:root 755
-done
+makedir pid root:root 755
+makedir public postfix:root 755
 for dir in incoming active bounce defer deferred flush saved corrupt; do
     makedir ${dir} postfix:root 700
     if [ -n "$chat" ]; then


[ CONTENT OF TYPE application/pgp-signature SKIPPED ]

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.