Exim before 4.86.2, when installed setuid root, allows local users to gain privileges via the perl_startup argument.

This update for exim fixes the following issues :

Changes in exim :

  - specify users with ref:mail, to make them dynamic.
    (boo#1046971)

  - CVE-2017-1000369: Fixed memory leaks that could be     exploited to 'stack crash' local privilege escalation     (boo#1044692)

  - Require user(mail) group(mail) to meet new users     handling in TW.

  - Prerequire permissions (fixes rpmlint).

  - conditionally disable DANE on SuSE versions with OpenSSL     < 1.0

  - CVE-2016-1531: when installed setuid root, allows local     users to gain privileges via the perl_startup argument. 

  - CVE-2016-9963: DKIM information leakage (boo#1015930)



  - Makefile tuning :

  + add sqlite support

  + disable WITH_OLD_DEMIME

  + enable AUTH_CYRUS_SASL

  + enable AUTH_TLS

  + enable SYSLOG_LONG_LINES

  + enable SUPPORT_PAM

  + MAX_NAMED_LIST=64

  + enable EXPERIMENTAL_DMARC

  + enable EXPERIMENTAL_EVENT

  + enable EXPERIMENTAL_PROXY

  + enable EXPERIMENTAL_CERTNAMES

  + enable EXPERIMENTAL_DSN

  + enable EXPERIMENTAL_DANE

  + enable EXPERIMENTAL_SOCKS

  + enable EXPERIMENTAL_INTERNATIONAL

It was discovered that Exim incorrectly filtered environment variables when used with the perl_startup configuration option. If the perl_startup option was enabled, a local attacker could use this issue to escalate their privileges to the root user. This issue has been fixed by having Exim clean the complete execution environment by default on startup, including any subprocesses such as transports that call other programs. This change in behaviour may break existing installations and can be adjusted by using two new configuration options, keep_environment and add_environment. (CVE-2016-1531)

Patrick William discovered that Exim incorrectly expanded mathematical comparisons twice. A local attacker could possibly use this issue to perform arbitrary file operations as the Exim user. This issue only affected Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2014-2972).

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.

A local root privilege escalation vulnerability was found in Exim, Debian's default mail transfer agent, in configurations using the'perl_startup' option (Only Exim via exim4-daemon-heavy enables Perl support).

To address the vulnerability, updated Exim versions clean the complete execution environment by default, affecting Exim and subprocesses such as transports calling other programs, and thus may break existing installations. New configuration options (keep_environment, add_environment) were introduced to adjust this behavior.

More information can be found in the upstream advisory at https://www.exim.org/static/doc/CVE-2016-1531.txt

This update to exim 4.86.2 fixes the following issues :

  - CVE-2016-1531: local privilege escalation for set-uid     root exim when using 'perl_startup' (boo#968844)

Important: Exim now cleans the complete execution environment by default. This affects Exim and subprocesses such as transports calling other programs. The following new options are supported to adjust this behaviour :

  - keep_environment

  - add_environment A warning will be printed upon startup     if none of these are configured.

Also includes upstream changes, improvements and bug fixes :

  - Support for using the system standard CA bundle.

  - New expansion items $config_file, $config_dir,     containing the file and directory name of the main     configuration file. Also $exim_version.

  - New 'malware=' support for Avast.

  - New 'spam=' variant option for Rspamd.

  - Assorted options on malware= and spam= scanners.

  - A commandline option to write a comment into the     logfile.

  - A logging option for slow DNS lookups.

  - New $(env (<variable>)) expansion.

  - A non-SMTP authenticator using information from TLS     client certificates.

  - Main option 'tls_eccurve' for selecting an Elliptic     Curve for TLS.

  - Main option 'dns_trust_aa' for trusting your local     nameserver at the same level as DNSSEC.

This is new version fixing local privilege escalation for set-uid root when using perl_startup.

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 Exim development team reports :

All installations having Exim set-uid root and using 'perl_startup' are vulnerable to a local privilege escalation. Any user who can start an instance of Exim (and this is normally any user) can gain root privileges. If you do not use 'perl_startup' you should be safe.

ID	Name	Product	Family	Severity
102834	openSUSE Security Update : exim (openSUSE-2017-980) (Stack Clash)	Nessus	SuSE Local Security Checks	high
89962	Ubuntu 14.04 LTS : Exim vulnerabilities (USN-2933-1)	Nessus	Ubuntu Local Security Checks	high
89926	Debian DSA-3517-1 : exim4 - security update	Nessus	Debian Local Security Checks	high
89909	openSUSE Security Update : exim (openSUSE-2016-326)	Nessus	SuSE Local Security Checks	high
89891	Fedora 23 : exim-4.86.2-1.fc23 (2016-e062971917)	Nessus	Fedora Local Security Checks	high
89881	Fedora 22 : exim-4.85.2-1.fc22 (2016-0e3ca94d88)	Nessus	Fedora Local Security Checks	high
89089	FreeBSD : exim -- local privillege escalation (7d09b9ee-e0ba-11e5-abc4-6fb07af136d2)	Nessus	FreeBSD Local Security Checks	high

Detections

Analytics

CVE-2016-1531

high

Tenable Plugins

high

high

high

high

high

high

high