Vulnerabilities > CVE-2011-0017 - Link Following vulnerability in Exim
Attack vector
UNKNOWN Attack complexity
UNKNOWN Privileges required
UNKNOWN Confidentiality impact
UNKNOWN Integrity impact
UNKNOWN Availability impact
UNKNOWN Summary
The open_log function in log.c in Exim 4.72 and earlier does not check the return value from (1) setuid or (2) setgid system calls, which allows local users to append log data to arbitrary files via a symlink attack.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Symlink Attack An attacker positions a symbolic link in such a manner that the targeted user or application accesses the link's endpoint, assuming that it is accessing a file with the link's name. The endpoint file may be either output or input. If the file is output, the result is that the endpoint is modified, instead of a file at the intended location. Modifications to the endpoint file may include appending, overwriting, corrupting, changing permissions, or other modifications. In some variants of this attack the attacker may be able to control the change to a file while in other cases they cannot. The former is especially damaging since the attacker may be able to grant themselves increased privileges or insert false information, but the latter can also be damaging as it can expose sensitive information or corrupt or destroy vital system or application files. Alternatively, the endpoint file may serve as input to the targeted application. This can be used to feed malformed input into the target or to cause the target to process different information, possibly allowing the attacker to control the actions of the target or to cause the target to expose information to the attacker. Moreover, the actions taken on the endpoint file are undertaken with the permissions of the targeted user or application, which may exceed the permissions that the attacker would normally have.
- 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.
- 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.
Nessus
NASL family SuSE Local Security Checks NASL id SUSE_11_2_EXIM-110207.NASL description Exim was updated to verify the return value of the setuid/setgid calls now. (CVE-2011-0017: CVSS v2 Base Score: 6.9 (AV:L/AC:M/Au:N/C:C/I:C/A:C): Link Following (CWE-59)) last seen 2020-06-01 modified 2020-06-02 plugin id 53716 published 2011-05-05 reporter This script is Copyright (C) 2011-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/53716 title openSUSE Security Update : exim (openSUSE-SU-2011:0105-1) code #%NASL_MIN_LEVEL 80502 # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from openSUSE Security Update exim-3922. # # The text description of this plugin is (C) SUSE LLC. # include("compat.inc"); if (description) { script_id(53716); script_version("1.5"); script_cvs_date("Date: 2019/10/25 13:36:40"); script_cve_id("CVE-2011-0017"); script_name(english:"openSUSE Security Update : exim (openSUSE-SU-2011:0105-1)"); script_summary(english:"Check for the exim-3922 patch"); script_set_attribute( attribute:"synopsis", value:"The remote openSUSE host is missing a security update." ); script_set_attribute( attribute:"description", value: "Exim was updated to verify the return value of the setuid/setgid calls now. (CVE-2011-0017: CVSS v2 Base Score: 6.9 (AV:L/AC:M/Au:N/C:C/I:C/A:C): Link Following (CWE-59))" ); script_set_attribute( attribute:"see_also", value:"https://bugzilla.novell.com/show_bug.cgi?id=668599" ); script_set_attribute( attribute:"see_also", value:"https://lists.opensuse.org/opensuse-updates/2011-02/msg00005.html" ); script_set_attribute(attribute:"solution", value:"Update the affected exim packages."); script_set_cvss_base_vector("CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:exim"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:eximon"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:eximstats-html"); script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:opensuse:11.2"); script_set_attribute(attribute:"patch_publication_date", value:"2011/02/07"); script_set_attribute(attribute:"plugin_publication_date", value:"2011/05/05"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 2011-2019 and is owned by Tenable, Inc. or an Affiliate thereof."); script_family(english:"SuSE Local Security Checks"); script_dependencies("ssh_get_info.nasl"); script_require_keys("Host/local_checks_enabled", "Host/SuSE/release", "Host/SuSE/rpm-list", "Host/cpu"); exit(0); } include("audit.inc"); include("global_settings.inc"); include("rpm.inc"); if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED); release = get_kb_item("Host/SuSE/release"); if (isnull(release) || release =~ "^(SLED|SLES)") audit(AUDIT_OS_NOT, "openSUSE"); if (release !~ "^(SUSE11\.2)$") audit(AUDIT_OS_RELEASE_NOT, "openSUSE", "11.2", release); if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING); ourarch = get_kb_item("Host/cpu"); if (!ourarch) audit(AUDIT_UNKNOWN_ARCH); if (ourarch !~ "^(i586|i686|x86_64)$") audit(AUDIT_ARCH_NOT, "i586 / i686 / x86_64", ourarch); flag = 0; if ( rpm_check(release:"SUSE11.2", reference:"exim-4.69-72.8.1") ) flag++; if ( rpm_check(release:"SUSE11.2", reference:"eximon-4.69-72.8.1") ) flag++; if ( rpm_check(release:"SUSE11.2", reference:"eximstats-html-4.69-72.8.1") ) flag++; if (flag) { if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get()); else security_warning(0); exit(0); } else { tested = pkg_tests_get(); if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested); else audit(AUDIT_PACKAGE_NOT_INSTALLED, "exim"); }
NASL family Debian Local Security Checks NASL id DEBIAN_DSA-2154.NASL description A design flaw (CVE-2010-4345 ) in exim4 allowed the local Debian-exim user to obtain root privileges by specifying an alternate configuration file using the -C option or by using the macro override facility (-D option). Unfortunately, fixing this vulnerability is not possible without some changes in exim4 last seen 2020-03-17 modified 2011-01-31 plugin id 51819 published 2011-01-31 reporter This script is Copyright (C) 2011-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/51819 title Debian DSA-2154-1 : exim4 - privilege escalation NASL family SuSE Local Security Checks NASL id SUSE_11_3_EXIM-110207.NASL description Exim was updated to verify the return value of the setuid/setgid calls now. (CVE-2011-0017: CVSS v2 Base Score: 6.9 (AV:L/AC:M/Au:N/C:C/I:C/A:C): Link Following (CWE-59)) last seen 2020-06-01 modified 2020-06-02 plugin id 75482 published 2014-06-13 reporter This script is Copyright (C) 2014-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/75482 title openSUSE Security Update : exim (openSUSE-SU-2011:0105-1) NASL family Ubuntu Local Security Checks NASL id UBUNTU_USN-1060-1.NASL description It was discovered that Exim contained a design flaw in the way it processed alternate configuration files. An attacker that obtained privileges of the last seen 2020-06-01 modified 2020-06-02 plugin id 51954 published 2011-02-11 reporter Ubuntu Security Notice (C) 2011-2019 Canonical, Inc. / NASL script (C) 2011-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/51954 title Ubuntu 6.06 LTS / 8.04 LTS / 9.10 / 10.04 LTS / 10.10 : exim4 vulnerabilities (USN-1060-1) NASL family FreeBSD Local Security Checks NASL id FREEBSD_PKG_44CCFAB0356411E08E810022190034C0.NASL description exim.org reports : CVE-2011-0017 - check return value of setuid/setgid. This is a privilege escalation vulnerability whereby the Exim run-time user can cause root to append content of the attacker last seen 2020-06-01 modified 2020-06-02 plugin id 51963 published 2011-02-14 reporter This script is Copyright (C) 2011-2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/51963 title FreeBSD : exim -- local privilege escalation (44ccfab0-3564-11e0-8e81-0022190034c0) NASL family SMTP problems NASL id EXIM_4_74.NASL description The remote host is running Exim, a message transfer agent. According to the version number in its banner, the installed version of Exim is earlier than 4.74 and thus potentially affected by a local privilege escalation vulnerability. If the remote host is running Linux, attackers can exploit this issue to append arbitrary data to files through symbolic link attacks. Successfully exploiting this issue allows local attackers with last seen 2020-06-01 modified 2020-06-02 plugin id 51861 published 2011-02-03 reporter This script is Copyright (C) 2011-2018 Tenable Network Security, Inc. source https://www.tenable.com/plugins/nessus/51861 title Exim < 4.74 Local Privilege Escalation NASL family Gentoo Local Security Checks NASL id GENTOO_GLSA-201401-32.NASL description The remote host is affected by the vulnerability described in GLSA-201401-32 (Exim: Multiple vulnerabilities) Multiple vulnerabilities have been discovered in Exim. Please review the CVE identifiers referenced below for details. Impact : A remote attacker could possibly execute arbitrary code with root privileges, or cause a Denial of Service condition. Workaround : There is no known workaround at this time. last seen 2020-06-01 modified 2020-06-02 plugin id 72159 published 2014-01-28 reporter This script is Copyright (C) 2014-2018 Tenable Network Security, Inc. source https://www.tenable.com/plugins/nessus/72159 title GLSA-201401-32 : Exim: Multiple vulnerabilities
References
- ftp://ftp.exim.org/pub/exim/ChangeLogs/ChangeLog-4.74
- http://lists.exim.org/lurker/message/20110126.034702.4d69c278.en.html
- http://lists.opensuse.org/opensuse-security-announce/2011-02/msg00004.html
- http://osvdb.org/70696
- http://secunia.com/advisories/43101
- http://secunia.com/advisories/43128
- http://secunia.com/advisories/43243
- http://www.debian.org/security/2011/dsa-2154
- http://www.securityfocus.com/bid/46065
- http://www.ubuntu.com/usn/USN-1060-1
- http://www.vupen.com/english/advisories/2011/0224
- http://www.vupen.com/english/advisories/2011/0245
- http://www.vupen.com/english/advisories/2011/0364
- http://www.vupen.com/english/advisories/2011/0464
- https://exchange.xforce.ibmcloud.com/vulnerabilities/65028
- ftp://ftp.exim.org/pub/exim/ChangeLogs/ChangeLog-4.74
- https://exchange.xforce.ibmcloud.com/vulnerabilities/65028
- http://www.vupen.com/english/advisories/2011/0464
- http://www.vupen.com/english/advisories/2011/0364
- http://www.vupen.com/english/advisories/2011/0245
- http://www.vupen.com/english/advisories/2011/0224
- http://www.ubuntu.com/usn/USN-1060-1
- http://www.securityfocus.com/bid/46065
- http://www.debian.org/security/2011/dsa-2154
- http://secunia.com/advisories/43243
- http://secunia.com/advisories/43128
- http://secunia.com/advisories/43101
- http://osvdb.org/70696
- http://lists.opensuse.org/opensuse-security-announce/2011-02/msg00004.html
- http://lists.exim.org/lurker/message/20110126.034702.4d69c278.en.html