Vulnerabilities > CVE-2019-3902 - Link Following vulnerability in multiple products

047910
CVSS 5.9 - MEDIUM
Attack vector
NETWORK
Attack complexity
HIGH
Privileges required
NONE
Confidentiality impact
NONE
Integrity impact
HIGH
Availability impact
NONE
network
high complexity
mercurial
redhat
debian
CWE-59
nessus
NVD
Published: 2019-04-22
Updated: 2020-07-31

Summary

A flaw was found in Mercurial before 4.9. It was possible to use symlinks and subrepositories to defeat Mercurial's path-checking logic and write files outside a repository.

Vulnerable Configurations

Part Description Count
Application
Mercurial
129
OS
Redhat
1
OS
Debian
1

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 familyPhotonOS Local Security Checks
    NASL idPHOTONOS_PHSA-2019-1_0-0235_MERCURIAL.NASL
    descriptionAn update of the mercurial package has been released.
    last seen2020-06-01
    modified2020-06-02
    plugin id125402
    published2019-05-28
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/125402
    titlePhoton OS 1.0: Mercurial PHSA-2019-1.0-0235
    code
    #
# (C) Tenable Network Security, Inc.
#

# The descriptive text and package checks in this plugin were
# extracted from VMware Security Advisory PHSA-2019-1.0-0235. The text
# itself is copyright (C) VMware, Inc.

include("compat.inc");

if (description)
{
  script_id(125402);
  script_version("1.2");
  script_cvs_date("Date: 2020/01/13");

  script_cve_id("CVE-2019-3902");

  script_name(english:"Photon OS 1.0: Mercurial PHSA-2019-1.0-0235");
  script_summary(english:"Checks the rpm output for the updated packages.");

  script_set_attribute(attribute:"synopsis", value:
"The remote PhotonOS host is missing multiple security updates.");
  script_set_attribute(attribute:"description", value:
"An update of the mercurial package has been released.");
  script_set_attribute(attribute:"see_also", value:"https://github.com/vmware/photon/wiki/Security-Updates-1.0-235.md");
  script_set_attribute(attribute:"solution", value:
"Update the affected Linux packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/AC:M/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:H/PR:L/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:"cvss_score_source", value:"CVE-2019-11599");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/11/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/05/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/05/28");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:vmware:photonos:mercurial");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:vmware:photonos:1.0");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"PhotonOS Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/PhotonOS/release", "Host/PhotonOS/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/PhotonOS/release");
if (isnull(release) || release !~ "^VMware Photon") audit(AUDIT_OS_NOT, "PhotonOS");
if (release !~ "^VMware Photon (?:Linux|OS) 1\.0(\D|$)") audit(AUDIT_OS_NOT, "PhotonOS 1.0");

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

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

flag = 0;

if (rpm_check(release:"PhotonOS-1.0", reference:"mercurial-4.5.3-3.ph1")) flag++;
if (rpm_check(release:"PhotonOS-1.0", reference:"mercurial-debuginfo-4.5.3-3.ph1")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "mercurial");
}
  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DLA-1764.NASL
    descriptionIt was discovered that there was a path traversal vulnerability in the
    last seen2020-06-01
    modified2020-06-02
    plugin id124306
    published2019-04-26
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/124306
    titleDebian DLA-1764-1 : mercurial security update
    code
    #
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory DLA-1764-1. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include("compat.inc");

if (description)
{
  script_id(124306);
  script_version("1.3");
  script_cvs_date("Date: 2020/01/22");

  script_cve_id("CVE-2019-3902");

  script_name(english:"Debian DLA-1764-1 : mercurial security update");
  script_summary(english:"Checks dpkg output for the updated packages.");

  script_set_attribute(
    attribute:"synopsis", 
    value:"The remote Debian host is missing a security update."
  );
  script_set_attribute(
    attribute:"description", 
    value:
"It was discovered that there was a path traversal vulnerability in the
'mercurial' distributed revision version control system.

Symbolic links and subrepositories could be used defeat Mercurial's
path-checking logic and write files outside the repository root.

For Debian 8 'Jessie', this issue has been fixed in mercurial version
3.1.2-2+deb8u7.

We recommend that you upgrade your mercurial packages.

NOTE: Tenable Network Security has extracted the preceding description
block directly from the DLA 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://lists.debian.org/debian-lts-announce/2019/04/msg00024.html"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://packages.debian.org/source/jessie/mercurial"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Upgrade the affected mercurial, and mercurial-common packages."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:N/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:H/PR:N/UI:N/S:U/C:N/I:H/A:N");
  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:debian:debian_linux:mercurial");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:mercurial-common");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:8.0");

  script_set_attribute(attribute:"vuln_publication_date", value:"2019/04/22");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/04/25");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/04/26");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2019-2020 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:"8.0", prefix:"mercurial", reference:"3.1.2-2+deb8u7")) flag++;
if (deb_check(release:"8.0", prefix:"mercurial-common", reference:"3.1.2-2+deb8u7")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:deb_report_get());
  else security_warning(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
  • NASL familyPhotonOS Local Security Checks
    NASL idPHOTONOS_PHSA-2019-2_0-0160_MERCURIAL.NASL
    descriptionAn update of the mercurial package has been released.
    last seen2020-06-01
    modified2020-06-02
    plugin id125397
    published2019-05-28
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/125397
    titlePhoton OS 2.0: Mercurial PHSA-2019-2.0-0160
    code
    #
# (C) Tenable Network Security, Inc.
#

# The descriptive text and package checks in this plugin were
# extracted from VMware Security Advisory PHSA-2019-2.0-0160. The text
# itself is copyright (C) VMware, Inc.

include("compat.inc");

if (description)
{
  script_id(125397);
  script_version("1.2");
  script_cvs_date("Date: 2020/01/13");

  script_cve_id("CVE-2019-3902");

  script_name(english:"Photon OS 2.0: Mercurial PHSA-2019-2.0-0160");
  script_summary(english:"Checks the rpm output for the updated packages.");

  script_set_attribute(attribute:"synopsis", value:
"The remote PhotonOS host is missing multiple security updates.");
  script_set_attribute(attribute:"description", value:
"An update of the mercurial package has been released.");
  script_set_attribute(attribute:"see_also", value:"https://github.com/vmware/photon/wiki/Security-Updates-2-160.md");
  script_set_attribute(attribute:"solution", value:
"Update the affected Linux packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:C/I:C/A:C");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:H/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:"cvss_score_source", value:"CVE-2019-11815");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");

  script_set_attribute(attribute:"vuln_publication_date", value:"2018/11/08");
  script_set_attribute(attribute:"patch_publication_date", value:"2019/05/23");
  script_set_attribute(attribute:"plugin_publication_date", value:"2019/05/28");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:vmware:photonos:mercurial");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:vmware:photonos:2.0");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"PhotonOS Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/PhotonOS/release", "Host/PhotonOS/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/PhotonOS/release");
if (isnull(release) || release !~ "^VMware Photon") audit(AUDIT_OS_NOT, "PhotonOS");
if (release !~ "^VMware Photon (?:Linux|OS) 2\.0(\D|$)") audit(AUDIT_OS_NOT, "PhotonOS 2.0");

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

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

flag = 0;

if (rpm_check(release:"PhotonOS-2.0", reference:"mercurial-4.5.3-3.ph2")) flag++;
if (rpm_check(release:"PhotonOS-2.0", reference:"mercurial-debuginfo-4.5.3-3.ph2")) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "mercurial");
}
  • NASL familyUbuntu Local Security Checks
    NASL idUBUNTU_USN-4086-1.NASL
    descriptionIt was discovered that Mercurial mishandled symlinks in subrepositories. An attacker could use this vulnerability to write arbitrary files to the target
    last seen2020-06-01
    modified2020-06-02
    plugin id127803
    published2019-08-12
    reporterUbuntu Security Notice (C) 2019-2020 Canonical, Inc. / NASL script (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/127803
    titleUbuntu 19.04 : Mercurial vulnerability (USN-4086-1)
  • NASL familyPhotonOS Local Security Checks
    NASL idPHOTONOS_PHSA-2019-3_0-0015_MERCURIAL.NASL
    descriptionAn update of the mercurial package has been released.
    last seen2020-06-01
    modified2020-06-02
    plugin id126116
    published2019-06-24
    reporterThis script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/126116
    titlePhoton OS 3.0: Mercurial PHSA-2019-3.0-0015

References