Vulnerabilities > CVE-2019-12524 - Missing Authentication for Critical Function vulnerability in multiple products

047910
CVSS 9.8 - CRITICAL
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
HIGH
Integrity impact
HIGH
Availability impact
HIGH
network
low complexity
squid-cache
debian
canonical
CWE-306
critical
nessus
NVD
Published: 2020-04-15
Updated: 2021-02-09

Summary

An issue was discovered in Squid through 4.7. When handling requests from users, Squid checks its rules to see if the request should be denied. Squid by default comes with rules to block access to the Cache Manager, which serves detailed server information meant for the maintainer. This rule is implemented via url_regex. The handler for url_regex rules URL decodes an incoming request. This allows an attacker to encode their URL to bypass the url_regex check, and gain access to the blocked resource.

Vulnerable Configurations

Part Description Count
Application
Squid-Cache
244
OS
Debian
2
OS
Canonical
2

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Choosing a Message/Channel Identifier on a Public/Multicast Channel
    Attackers aware that more data is being fed into a multicast or public information distribution means can 'select' information bound only for another client, even if the distribution means itself forces users to authenticate in order to connect initially. Doing so allows the attacker to gain access to possibly privileged information, possibly perpetrate other attacks through the distribution means by impersonation. If the channel/message being manipulated is an input rather than output mechanism for the system, (such as a command bus), this style of attack could change its identifier from a less privileged to more so privileged channel or command.
  • Using Unpublished Web Service APIs
    An attacker searches for and invokes Web Services APIs that the target system designers did not intend to be publicly available. If these APIs fail to authenticate requests the attacker may be able to invoke services and/or gain privileges they are not authorized for.
  • Manipulating Writeable Terminal Devices
    This attack exploits terminal devices that allow themselves to be written to by other users. The attacker sends command strings to the target terminal device hoping that the target user will hit enter and thereby execute the malicious command with their privileges. The attacker can send the results (such as copying /etc/passwd) to a known directory and collect once the attack has succeeded.
  • Cross Site Request Forgery (aka Session Riding)
    An attacker crafts malicious web links and distributes them (via web pages, email, etc.), typically in a targeted manner, hoping to induce users to click on the link and execute the malicious action against some third-party application. If successful, the action embedded in the malicious link will be processed and accepted by the targeted application with the users' privilege level. This type of attack leverages the persistence and implicit trust placed in user session cookies by many web applications today. In such an architecture, once the user authenticates to an application and a session cookie is created on the user's system, all following transactions for that session are authenticated using that cookie including potential actions initiated by an attacker and simply "riding" the existing session cookie.

Nessus

  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DSA-4682.NASL
    descriptionMultiple security issues were discovered in the Squid proxy caching server, which could result in the bypass of security filters, information disclosure, the execution of arbitrary code or denial of service.
    last seen2020-05-15
    modified2020-05-11
    plugin id136430
    published2020-05-11
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/136430
    titleDebian DSA-4682-1 : squid - security update
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Debian Security Advisory DSA-4682. The text 
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(136430);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/13");

  script_cve_id("CVE-2019-12519", "CVE-2019-12520", "CVE-2019-12521", "CVE-2019-12523", "CVE-2019-12524", "CVE-2019-12526", "CVE-2019-12528", "CVE-2019-18676", "CVE-2019-18677", "CVE-2019-18678", "CVE-2019-18679", "CVE-2020-11945", "CVE-2020-8449", "CVE-2020-8450");
  script_xref(name:"DSA", value:"4682");

  script_name(english:"Debian DSA-4682-1 : squid - security update");
  script_summary(english:"Checks dpkg output for the updated package");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Debian host is missing a security-related update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"Multiple security issues were discovered in the Squid proxy caching
server, which could result in the bypass of security filters,
information disclosure, the execution of arbitrary code or denial of
service."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://security-tracker.debian.org/tracker/source-package/squid"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/buster/squid"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.debian.org/security/2020/dsa-4682"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"Upgrade the squid packages.

For the stable distribution (buster), these problems have been fixed
in version 4.6-1+deb10u2."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-8450");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:squid");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:10.0");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/11/26");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/05/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/11");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Debian Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l");

  exit(0);
}


include("audit.inc");
include("debian_package.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian");
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (deb_check(release:"10.0", prefix:"squid", reference:"4.6-1+deb10u2")) flag++;
if (deb_check(release:"10.0", prefix:"squid-cgi", reference:"4.6-1+deb10u2")) flag++;
if (deb_check(release:"10.0", prefix:"squid-common", reference:"4.6-1+deb10u2")) flag++;
if (deb_check(release:"10.0", prefix:"squid-purge", reference:"4.6-1+deb10u2")) flag++;
if (deb_check(release:"10.0", prefix:"squid3", reference:"4.6-1+deb10u2")) flag++;
if (deb_check(release:"10.0", prefix:"squidclient", reference:"4.6-1+deb10u2")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:deb_report_get());
  else security_hole(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
  • NASL familySuSE Local Security Checks
    NASL idSUSE_SU-2020-1227-1.NASL
    descriptionThis update for squid fixes the following issues : CVE-2019-12519, CVE-2019-12521: fixes incorrect buffer handling that can result in cache poisoning, remote execution, and denial of service attacks when processing ESI responses (bsc#1169659). CVE-2020-11945: fixes a potential remote execution vulnerability when using HTTP Digest Authentication (bsc#1170313). CVE-2019-12520, CVE-2019-12524: fixes a potential ACL bypass, cache-bypass and cross-site scripting attack when processing invalid HTTP Request messages (bsc#1170423). Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-05-21
    modified2020-05-15
    plugin id136659
    published2020-05-15
    reporterThis script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/136659
    titleSUSE SLES12 Security Update : squid (SUSE-SU-2020:1227-1)
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from SUSE update advisory SUSE-SU-2020:1227-1.
# The text itself is copyright (C) SUSE.
#

include("compat.inc");

if (description)
{
  script_id(136659);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/05/19");

  script_cve_id("CVE-2019-12519", "CVE-2019-12520", "CVE-2019-12521", "CVE-2019-12524", "CVE-2020-11945");

  script_name(english:"SUSE SLES12 Security Update : squid (SUSE-SU-2020:1227-1)");
  script_summary(english:"Checks rpm output for the updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote SUSE host is missing one or more security updates."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"This update for squid fixes the following issues :

CVE-2019-12519, CVE-2019-12521: fixes incorrect buffer handling that
can result in cache poisoning, remote execution, and denial of service
attacks when processing ESI responses (bsc#1169659).

CVE-2020-11945: fixes a potential remote execution vulnerability when
using HTTP Digest Authentication (bsc#1170313).

CVE-2019-12520, CVE-2019-12524: fixes a potential ACL bypass,
cache-bypass and cross-site scripting attack when processing invalid
HTTP Request messages (bsc#1170423).

Note that Tenable Network Security has extracted the preceding
description block directly from the SUSE security advisory. Tenable
has attempted to automatically clean and format it as much as possible
without introducing additional issues."
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.suse.com/show_bug.cgi?id=1169659"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.suse.com/show_bug.cgi?id=1170313"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://bugzilla.suse.com/show_bug.cgi?id=1170423"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.suse.com/security/cve/CVE-2019-12519/"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.suse.com/security/cve/CVE-2019-12520/"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.suse.com/security/cve/CVE-2019-12521/"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.suse.com/security/cve/CVE-2019-12524/"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://www.suse.com/security/cve/CVE-2020-11945/"
  );
  # https://www.suse.com/support/update/announcement/2020/suse-su-20201227-1/
  script_set_attribute(
    attribute:"see_also",
    value:"http://www.nessus.org/u?9cd91a94"
  );
  script_set_attribute(
    attribute:"solution", 
    value:
"To install this SUSE Security Update use the SUSE recommended
installation methods like YaST online_update or 'zypper patch'.

Alternatively you can run the command listed for your product :

SUSE OpenStack Cloud Crowbar 8 :

zypper in -t patch SUSE-OpenStack-Cloud-Crowbar-8-2020-1227=1

SUSE OpenStack Cloud 8 :

zypper in -t patch SUSE-OpenStack-Cloud-8-2020-1227=1

SUSE OpenStack Cloud 7 :

zypper in -t patch SUSE-OpenStack-Cloud-7-2020-1227=1

SUSE Linux Enterprise Server for SAP 12-SP3 :

zypper in -t patch SUSE-SLE-SAP-12-SP3-2020-1227=1

SUSE Linux Enterprise Server for SAP 12-SP2 :

zypper in -t patch SUSE-SLE-SAP-12-SP2-2020-1227=1

SUSE Linux Enterprise Server 12-SP4 :

zypper in -t patch SUSE-SLE-SERVER-12-SP4-2020-1227=1

SUSE Linux Enterprise Server 12-SP3-LTSS :

zypper in -t patch SUSE-SLE-SERVER-12-SP3-2020-1227=1

SUSE Linux Enterprise Server 12-SP3-BCL :

zypper in -t patch SUSE-SLE-SERVER-12-SP3-BCL-2020-1227=1

SUSE Linux Enterprise Server 12-SP2-LTSS :

zypper in -t patch SUSE-SLE-SERVER-12-SP2-2020-1227=1

SUSE Linux Enterprise Server 12-SP2-BCL :

zypper in -t patch SUSE-SLE-SERVER-12-SP2-BCL-2020-1227=1

SUSE Enterprise Storage 5 :

zypper in -t patch SUSE-Storage-5-2020-1227=1

HPE Helion Openstack 8 :

zypper in -t patch HPE-Helion-OpenStack-8-2020-1227=1"
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:suse_linux:squid");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:suse_linux:squid-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:suse_linux:squid-debugsource");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:suse_linux:12");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/04/15");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/05/08");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/15");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2020 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/cpu", "Host/SuSE/release", "Host/SuSE/rpm-list");

  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, "SUSE");
os_ver = pregmatch(pattern: "^(SLE(S|D)\d+)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "SUSE");
os_ver = os_ver[1];
if (! preg(pattern:"^(SLES12)$", string:os_ver)) audit(AUDIT_OS_NOT, "SUSE SLES12", "SUSE " + os_ver);

if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if (cpu !~ "^i[3-6]86$" && "x86_64" >!< cpu && "s390x" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "SUSE " + os_ver, cpu);

sp = get_kb_item("Host/SuSE/patchlevel");
if (isnull(sp)) sp = "0";
if (os_ver == "SLES12" && (! preg(pattern:"^(2|3|4)$", string:sp))) audit(AUDIT_OS_NOT, "SLES12 SP2/3/4", os_ver + " SP" + sp);


flag = 0;
if (rpm_check(release:"SLES12", sp:"4", reference:"squid-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"4", reference:"squid-debuginfo-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"4", reference:"squid-debugsource-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"3", cpu:"x86_64", reference:"squid-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"3", cpu:"x86_64", reference:"squid-debuginfo-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"3", cpu:"x86_64", reference:"squid-debugsource-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"3", reference:"squid-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"3", reference:"squid-debuginfo-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"3", reference:"squid-debugsource-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"2", cpu:"x86_64", reference:"squid-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"2", cpu:"x86_64", reference:"squid-debuginfo-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"2", cpu:"x86_64", reference:"squid-debugsource-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"2", reference:"squid-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"2", reference:"squid-debuginfo-3.5.21-26.23.1")) flag++;
if (rpm_check(release:"SLES12", sp:"2", reference:"squid-debugsource-3.5.21-26.23.1")) flag++;


if (flag)
{
  set_kb_item(name:'www/0/XSS', value:TRUE);
  if (report_verbosity > 0) security_hole(port:0, extra:rpm_report_get());
  else security_hole(0);
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "squid");
}

References