ID CVE-2016-1531
Summary Exim before 4.86.2, when installed setuid root, allows local users to gain privileges via the perl_startup argument.
References
Vulnerable Configurations
  • Exim 4.86
    cpe:2.3:a:exim:exim:4.86
CVSS
Base: 6.9 (as of 08-04-2016 - 14:57)
Impact:
Exploitability:
CWE CWE-264
CAPEC
  • Accessing, Modifying or Executing Executable Files
    An attack of this type exploits a system's configuration that allows an attacker to either directly access an executable file, for example through shell access; or in a possible worst case allows an attacker to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
  • Leverage Executable Code in Non-Executable Files
    An attack of this type exploits a system's trust in configuration and resource files, when the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high. The attack can be directed at a client system, such as causing buffer overrun through loading seemingly benign image files, as in Microsoft Security Bulletin MS04-028 where specially crafted JPEG files could cause a buffer overrun once loaded into the browser. Another example targets clients reading pdf files. In this case the attacker simply appends javascript to the end of a legitimate url for a pdf (http://www.gnucitizen.org/blog/danger-danger-danger/) http://path/to/pdf/file.pdf#whatever_name_you_want=javascript:your_code_here The client assumes that they are reading a pdf, but the attacker has modified the resource and loaded executable javascript into the client's browser process. The attack can also target server processes. The attacker edits the resource or configuration file, for example a web.xml file used to configure security permissions for a J2EE app server, adding role name "public" grants all users with the public role the ability to use the administration functionality. The server trusts its configuration file to be correct, but when they are manipulated, the attacker gains full control.
  • Blue Boxing
    This type of attack against older telephone switches and trunks has been around for decades. A tone is sent by an adversary to impersonate a supervisor signal which has the effect of rerouting or usurping command of the line. While the US infrastructure proper may not contain widespread vulnerabilities to this type of attack, many companies are connected globally through call centers and business process outsourcing. These international systems may be operated in countries which have not upgraded Telco infrastructure and so are vulnerable to Blue boxing. Blue boxing is a result of failure on the part of the system to enforce strong authorization for administrative functions. While the infrastructure is different than standard current applications like web applications, there are historical lessons to be learned to upgrade the access control for administrative functions.
  • Restful Privilege Elevation
    Rest uses standard HTTP (Get, Put, Delete) style permissions methods, but these are not necessarily correlated generally with back end programs. Strict interpretation of HTTP get methods means that these HTTP Get services should not be used to delete information on the server, but there is no access control mechanism to back up this logic. This means that unless the services are properly ACL'd and the application's service implementation are following these guidelines then an HTTP request can easily execute a delete or update on the server side. The attacker identifies a HTTP Get URL such as http://victimsite/updateOrder, which calls out to a program to update orders on a database or other resource. The URL is not idempotent so the request can be submitted multiple times by the attacker, additionally, the attacker may be able to exploit the URL published as a Get method that actually performs updates (instead of merely retrieving data). This may result in malicious or inadvertent altering of data on the server.
  • Target Programs with Elevated Privileges
    This attack targets programs running with elevated privileges. The attacker would try to leverage a bug in the running program and get arbitrary code to execute with elevated privileges. For instance an attacker would look for programs that write to the system directories or registry keys (such as HKLM, which stores a number of critical Windows environment variables). These programs are typically running with elevated privileges and have usually not been designed with security in mind. Such programs are excellent exploit targets because they yield lots of power when they break. The malicious user try to execute its code at the same level as a privileged system call.
  • Manipulating Input to File System Calls
    An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
Access
VectorComplexityAuthentication
LOCAL MEDIUM NONE
Impact
ConfidentialityIntegrityAvailability
COMPLETE COMPLETE COMPLETE
exploit-db via4
  • description Exim "perl_startup" Privilege Escalation. CVE-2016-1531. Local exploit for linux platform
    file exploits/linux/local/39702.rb
    id EDB-ID:39702
    last seen 2016-04-15
    modified 2016-04-15
    platform linux
    port
    published 2016-04-15
    reporter metasploit
    source https://www.exploit-db.com/download/39702/
    title Exim "perl_startup" Privilege Escalation
    type local
  • description exim 4.84-3 - Local Root Exploit. CVE-2016-1531. Local exploit for linux platform
    file exploits/linux/local/39535.sh
    id EDB-ID:39535
    last seen 2016-03-10
    modified 2016-03-09
    platform linux
    port
    published 2016-03-09
    reporter Hacker Fantastic
    source https://www.exploit-db.com/download/39535/
    title exim <= 4.84-3 - Local Root Exploit
    type local
  • description Exim < 4.86.2 - Local Root Privilege Escalation. CVE-2016-1531. Local exploit for linux platform
    file exploits/linux/local/39549.txt
    id EDB-ID:39549
    last seen 2016-03-11
    modified 2016-03-10
    platform linux
    port
    published 2016-03-10
    reporter Dawid Golunski
    source https://www.exploit-db.com/download/39549/
    title Exim < 4.86.2 - Local Root Privilege Escalation
    type local
metasploit via4
description This module exploits a Perl injection vulnerability in Exim < 4.86.2 given the presence of the "perl_startup" configuration parameter.
id MSF:EXPLOIT/UNIX/LOCAL/EXIM_PERL_STARTUP
last seen 2019-03-28
modified 2018-11-16
published 2016-04-05
reliability Excellent
reporter Rapid7
source https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/unix/local/exim_perl_startup.rb
title Exim "perl_startup" Privilege Escalation
nessus via4
  • NASL family FreeBSD Local Security Checks
    NASL id FREEBSD_PKG_7D09B9EEE0BA11E5ABC46FB07AF136D2.NASL
    description 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.
    last seen 2019-02-21
    modified 2018-11-10
    plugin id 89089
    published 2016-03-03
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=89089
    title FreeBSD : exim -- local privillege escalation (7d09b9ee-e0ba-11e5-abc4-6fb07af136d2)
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2016-0E3CA94D88.NASL
    description 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.
    last seen 2019-02-21
    modified 2016-12-08
    plugin id 89881
    published 2016-03-14
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=89881
    title Fedora 22 : exim-4.85.2-1.fc22 (2016-0e3ca94d88)
  • NASL family Debian Local Security Checks
    NASL id DEBIAN_DSA-3517.NASL
    description 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
    last seen 2019-02-21
    modified 2018-11-10
    plugin id 89926
    published 2016-03-15
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=89926
    title Debian DSA-3517-1 : exim4 - security update
  • NASL family SuSE Local Security Checks
    NASL id OPENSUSE-2016-326.NASL
    description 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 {}} 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.
    last seen 2019-02-21
    modified 2016-12-07
    plugin id 89909
    published 2016-03-14
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=89909
    title openSUSE Security Update : exim (openSUSE-2016-326)
  • NASL family Ubuntu Local Security Checks
    NASL id UBUNTU_USN-2933-1.NASL
    description 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.
    last seen 2019-02-21
    modified 2018-12-01
    plugin id 89962
    published 2016-03-16
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=89962
    title Ubuntu 12.04 LTS / 14.04 LTS / 15.10 : exim4 vulnerabilities (USN-2933-1)
  • NASL family SuSE Local Security Checks
    NASL id OPENSUSE-2017-980.NASL
    description 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
    last seen 2019-02-21
    modified 2017-08-30
    plugin id 102834
    published 2017-08-30
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=102834
    title openSUSE Security Update : exim (openSUSE-2017-980) (Stack Clash)
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2016-E062971917.NASL
    description 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.
    last seen 2019-02-21
    modified 2016-12-08
    plugin id 89891
    published 2016-03-14
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=89891
    title Fedora 23 : exim-4.86.2-1.fc23 (2016-e062971917)
packetstorm via4
refmap via4
confirm http://www.exim.org/static/doc/CVE-2016-1531.txt
debian DSA-3517
exploit-db
  • 39535
  • 39549
  • 39702
misc
sectrack 1035512
suse openSUSE-SU-2016:0721
ubuntu USN-2933-1
Last major update 02-12-2016 - 22:21
Published 07-04-2016 - 19:59
Last modified 07-09-2017 - 21:29
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