Dovecot didn't properly treat negative access rights therefore allowing attackers to bypass intended access restrictions (CVE-2008-4577)

An updated dovecot package that corrects two security flaws and various bugs is now available for Red Hat Enterprise Linux 5.

This update has been rated as having low security impact by the Red Hat Security Response Team.

Dovecot is an IMAP server for Linux and UNIX-like systems, primarily written with security in mind.

A flaw was found in Dovecot's ACL plug-in. The ACL plug-in treated negative access rights as positive rights, which could allow an attacker to bypass intended access restrictions. (CVE-2008-4577)

A password disclosure flaw was found with Dovecot's configuration file. If a system had the 'ssl_key_password' option defined, any local user could view the SSL key password. (CVE-2008-4870)

Note: This flaw did not allow the attacker to acquire the contents of the SSL key. The password has no value without the key file which arbitrary users should not have read access to.

To better protect even this value, however, the dovecot.conf file now supports the '!include_try' directive. The ssl_key_password option should be moved from dovecot.conf to a new file owned by, and only readable and writable by, root (ie 0600). This file should be referenced from dovecot.conf by setting the '!include_try [/path/to/password/file]' option.

Additionally, this update addresses the following bugs :

* the dovecot init script -- /etc/rc.d/init.d/dovecot -- did not check if the dovecot binary or configuration files existed. It also used the wrong pid file for checking the dovecot service's status. This update includes a new init script that corrects these errors.

* the %files section of the dovecot spec file did not include '%dir %{ssldir}/private'. As a consequence, the /etc/pki/private/ directory was not owned by dovecot. (Note: files inside /etc/pki/private/ were and are owned by dovecot.) With this update, the missing line has been added to the spec file, and the noted directory is now owned by dovecot.

* in some previously released versions of dovecot, the authentication process accepted (and passed along un-escaped) passwords containing characters that had special meaning to dovecot's internal protocols.
This updated release prevents such passwords from being passed back, instead returning the error, 'Attempted login with password having illegal chars'.

Note: dovecot versions previously shipped with Red Hat Enterprise Linux 5 did not allow this behavior. This update addresses the issue above but said issue was only present in versions of dovecot not previously included with Red Hat Enterprise Linux 5.

Users of dovecot are advised to upgrade to this updated package, which addresses these vulnerabilities and resolves these issues.

The ACL plugin in dovecot prior to version 1.1.4 treated negative access rights as though they were positive access rights, which allowed attackers to bypass intended access restrictions (CVE-2008-4577).

The ACL plugin in dovecot prior to version 1.1.4 allowed attackers to bypass intended access restrictions by using the 'k' right to create unauthorized 'parent/child/child' mailboxes (CVE-2008-4578).

In addition, two bugs were discovered in the dovecot package shipped with Mandriva Linux 2009.0. The default permissions on the dovecot.conf configuration file were too restrictive, which prevents the use of dovecot's 'deliver' command as a non-root user. Secondly, dovecot should not start until after ntpd, if ntpd is active, because if ntpd corrects the time backwards while dovecot is running, dovecot will quit automatically, with the log message 'Time just moved backwards by X seconds. This might cause a lot of problems, so I'll just kill myself now.' The update resolves both these problems. The default permissions on dovecot.conf now allow the 'deliver' command to read the file. Note that if you edited dovecot.conf at all prior to installing the update, the new permissions may not be applied. If you find the 'deliver' command still does not work following the update, please run these commands as root :

# chmod 0640 /etc/dovecot.conf # chown root:mail /etc/dovecot.conf

Dovecot's initialization script now configures it to start after the ntpd service, to ensure ntpd resetting the clock does not interfere with Dovecot operation.

This package corrects the above-noted bugs and security issues by upgrading to the latest dovecot 1.1.6, which also provides additional bug fixes.

Timo Sirainen reports in dovecot 1.1.4 release notes :

ACL plugin fixes: Negative rights were actually treated as positive rights. 'k' right didn't prevent creating parent/child/child mailbox.
ACL groups weren't working.

A flaw was found in Dovecot's ACL plug-in. The ACL plug-in treated negative access rights as positive rights, which could allow an attacker to bypass intended access restrictions. (CVE-2008-4577)

A password disclosure flaw was found with Dovecot's configuration file. If a system had the 'ssl_key_password' option defined, any local user could view the SSL key password. (CVE-2008-4870)

Note: This flaw did not allow the attacker to acquire the contents of the SSL key. The password has no value without the key file which arbitrary users should not have read access to.

To better protect even this value, however, the dovecot.conf file now supports the '!include_try' directive. The ssl_key_password option should be moved from dovecot.conf to a new file owned by, and only readable and writable by, root (ie 0600). This file should be referenced from dovecot.conf by setting the '!include_try [/path/to/password/file]' option.

Additionally, this update addresses the following bugs :

  - the dovecot init script -- /etc/rc.d/init.d/dovecot --     did not check if the dovecot binary or configuration     files existed. It also used the wrong pid file for     checking the dovecot service's status. This update     includes a new init script that corrects these errors.

  - the %files section of the dovecot spec file did not     include '%dir %{ssldir}/private'. As a consequence, the     /etc/pki/private/ directory was not owned by dovecot.
    (Note: files inside /etc/pki/private/ were and are owned     by dovecot.) With this update, the missing line has been     added to the spec file, and the noted directory is now     owned by dovecot.

  - in some previously released versions of dovecot, the     authentication process accepted (and passed along     un-escaped) passwords containing characters that had     special meaning to dovecot's internal protocols. This     updated release prevents such passwords from being     passed back, instead returning the error, 'Attempted     login with password having illegal chars'.

Note: dovecot versions previously shipped with Scientific Linux 5 did not allow this behavior. This update addresses the issue above but said issue was only present in versions of dovecot not previously included with Scientific Linux 5.

The remote host is affected by the vulnerability described in GLSA-200812-16 (Dovecot: Multiple vulnerabilities)

    Several vulnerabilities were found in Dovecot:
    The 'k'     right in the acl_plugin does not work as expected (CVE-2008-4577,     CVE-2008-4578)     The dovecot.conf is world-readable, providing     improper protection for the ssl_key_password setting     (CVE-2008-4870)     A permanent Denial of Service with broken mail     headers is possible (CVE-2008-4907)   Impact :

    These vulnerabilities might allow a remote attacker to cause a Denial     of Service, to circumvent security restrictions or allow local     attackers to disclose the passphrase of the SSL private key.
  Workaround :

    There is no known workaround at this time.

fix handling of negative rights in the ACL plugin

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Oracle Linux 5 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2009-0205 advisory.

    - Resolves: #436287, CVE-2008-4870
    - Resolves: #469015, CVE-2008-4577

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It was discovered that the ACL plugin in Dovecot would incorrectly handle negative access rights. An attacker could exploit this flaw to access the Dovecot server, bypassing the intended access restrictions.
This only affected Ubuntu 8.04 LTS. (CVE-2008-4577)

It was discovered that the ManageSieve service in Dovecot incorrectly handled '..' in script names. A remote attacker could exploit this to read and modify arbitrary sieve files on the server. This only affected Ubuntu 8.10. (CVE-2008-5301)

It was discovered that the Sieve plugin in Dovecot incorrectly handled certain sieve scripts. An authenticated user could exploit this with a crafted sieve script to cause a denial of service or possibly execute arbitrary code. (CVE-2009-2632, CVE-2009-3235).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	Name	Product	Family	Published	Updated	Severity
39952	openSUSE Security Update : dovecot (dovecot-504)	Nessus	SuSE Local Security Checks	7/21/2009	1/14/2021	medium
35433	RHEL 5 : dovecot (RHSA-2009:0205)	Nessus	Red Hat Local Security Checks	1/21/2009	1/14/2021	medium
38066	Mandriva Linux Security Advisory : dovecot (MDVSA-2008:232)	Nessus	Mandriva Local Security Checks	4/23/2009	1/6/2021	medium
34838	FreeBSD : dovecot -- ACL plugin bypass vulnerabilities (75c24c1d-b688-11dd-88fd-001c2514716c)	Nessus	FreeBSD Local Security Checks	11/21/2008	1/6/2021	medium
60524	Scientific Linux Security Update : dovecot on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	8/1/2012	1/14/2021	medium
35108	GLSA-200812-16 : Dovecot: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	12/15/2008	1/6/2021	medium
34670	Fedora 9 : dovecot-1.0.15-14.fc9 (2008-9202)	Nessus	Fedora Local Security Checks	10/31/2008	1/11/2021	medium
180610	Oracle Linux 5 : dovecot (ELSA-2009-0205)	Nessus	Oracle Linux Local Security Checks	9/7/2023	10/22/2024	high
34673	Fedora 8 : dovecot-1.0.15-14.fc8 (2008-9232)	Nessus	Fedora Local Security Checks	10/31/2008	1/11/2021	medium
35677	openSUSE 10 Security Update : dovecot (dovecot-5986)	Nessus	SuSE Local Security Checks	2/13/2009	1/14/2021	medium
41940	Ubuntu 8.04 LTS / 8.10 / 9.04 : dovecot vulnerabilities (USN-838-1)	Nessus	Ubuntu Local Security Checks	9/29/2009	1/19/2021	high

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