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

The remote Redhat Enterprise Linux 4 host has one or more packages installed that are affected by a vulnerability that has been acknowledged by the vendor but will not be patched.

  - exim: local root privilege escalation for configurations with perl_startup (CVE-2016-1531)

Note that Nessus has not tested for this issue but has instead relied on the package manager's report that the package is installed.

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.

The remote Redhat Enterprise Linux 5 host has one or more packages installed that are affected by multiple vulnerabilities that have been acknowledged by the vendor but will not be patched.

  - exim: out-of-bounds access in string_interpret_escape() leading to buffer overflow in the SMTP delivery     process (CVE-2019-15846)

  - Exim before 4.86.2, when installed setuid root, allows local users to gain privileges via the perl_startup     argument. (CVE-2016-1531)

  - Exim supports the use of multiple -p command line arguments which are malloc()'ed and never free()'ed,     used in conjunction with other issues allows attackers to cause arbitrary code execution. This affects     exim version 4.89 and earlier. Please note that at this time upstream has released a patch (commit     65e061b76867a9ea7aeeb535341b790b90ae6c21), but it is not known if a new point release is available that     addresses this issue at this time. (CVE-2017-1000369)

  - An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a     handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.
    (CVE-2018-6789)

  - Exim through 4.93 has an out-of-bounds read in the SPA authenticator that could result in SPA/NTLM     authentication bypass in auths/spa.c and auths/auth-spa.c. (CVE-2020-12783)

  - A UNIX Symbolic Link (Symlink) Following vulnerability in the packaging of exim in openSUSE Factory allows     local attackers to escalate from user mail to root. This issue affects: openSUSE Factory exim versions     prior to 4.93.0.4-3.1. (CVE-2020-8015)

Note that Nessus has not tested for these issues but has instead relied on the package manager's report that the package is installed.

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.

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.

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

ID	Name	Product	Family	Published	Updated	Severity
89926	Debian DSA-3517-1 : exim4 - security update	Nessus	Debian Local Security Checks	3/15/2016	1/11/2021	high
195613	RHEL 4 : exim (Unpatched Vulnerability)	Nessus	Red Hat Local Security Checks	5/11/2024	5/13/2024	high
89891	Fedora 23 : exim-4.86.2-1.fc23 (2016-e062971917)	Nessus	Fedora Local Security Checks	3/14/2016	1/11/2021	high
89089	FreeBSD : exim -- local privillege escalation (7d09b9ee-e0ba-11e5-abc4-6fb07af136d2)	Nessus	FreeBSD Local Security Checks	3/3/2016	1/4/2021	high
195635	RHEL 5 : exim (Unpatched Vulnerability)	Nessus	Red Hat Local Security Checks	5/11/2024	5/13/2024	critical
89881	Fedora 22 : exim-4.85.2-1.fc22 (2016-0e3ca94d88)	Nessus	Fedora Local Security Checks	3/14/2016	1/11/2021	high
89909	openSUSE Security Update : exim (openSUSE-2016-326)	Nessus	SuSE Local Security Checks	3/14/2016	1/19/2021	high
89962	Ubuntu 14.04 LTS : Exim vulnerabilities (USN-2933-1)	Nessus	Ubuntu Local Security Checks	3/16/2016	10/20/2023	high
102834	openSUSE Security Update : exim (openSUSE-2017-980) (Stack Clash)	Nessus	SuSE Local Security Checks	8/30/2017	1/19/2021	high

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