Vulnerabilities > CVE-2019-12520 - Improper Input Validation vulnerability in multiple products

047910
CVSS 5.0 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
PARTIAL
Integrity impact
NONE
Availability impact
NONE
network
low complexity
squid-cache
canonical
debian
CWE-20
nessus
NVD
Published: 2020-04-15
Updated: 2021-02-11

Summary

An issue was discovered in Squid through 4.7 and 5. When receiving a request, Squid checks its cache to see if it can serve up a response. It does this by making a MD5 hash of the absolute URL of the request. If found, it servers the request. The absolute URL can include the decoded UserInfo (username and password) for certain protocols. This decoded info is prepended to the domain. This allows an attacker to provide a username that has special characters to delimit the domain, and treat the rest of the URL as a path or query string. An attacker could first make a request to their domain using an encoded username, then when a request for the target domain comes in that decodes to the exact URL, it will serve the attacker's HTML instead of the real HTML. On Squid servers that also act as reverse proxies, this allows an attacker to gain access to features that only reverse proxies can use, such as ESI.

Vulnerable Configurations

Part Description Count
Application
Squid-Cache
240
OS
Canonical
2
OS
Debian
2

Common Weakness Enumeration (CWE)

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Buffer Overflow via Environment Variables
    This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
  • Server Side Include (SSI) Injection
    An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
  • Cross Zone Scripting
    An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
  • Cross Site Scripting through Log Files
    An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
  • Command Line Execution through SQL Injection
    An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

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