Vulnerabilities > CVE-2017-9780 - Incorrect Permission Assignment for Critical Resource vulnerability in multiple products

047910
CVSS 7.2 - HIGH
Attack vector
LOCAL
Attack complexity
LOW
Privileges required
NONE
Confidentiality impact
COMPLETE
Integrity impact
COMPLETE
Availability impact
COMPLETE
local
low complexity
flatpak
debian
CWE-732
nessus

Summary

In Flatpak before 0.8.7, a third-party app repository could include malicious apps that contain files with inappropriate permissions, for example setuid or world-writable. The files are deployed with those permissions, which would let a local attacker run the setuid executable or write to the world-writable location. In the case of the "system helper" component, files deployed as part of the app are owned by root, so in the worst case they could be setuid root.

Common Attack Pattern Enumeration and Classification (CAPEC)

  • Accessing Functionality Not Properly Constrained by ACLs
    In applications, particularly web applications, access to functionality is mitigated by the authorization framework, whose job it is to map ACLs to elements of the application's functionality; particularly URL's for web apps. In the case that the administrator failed to specify an ACL for a particular element, an attacker may be able to access it with impunity. An attacker with the ability to access functionality not properly constrained by ACLs can obtain sensitive information and possibly compromise the entire application. Such an attacker can access resources that must be available only to users at a higher privilege level, can access management sections of the application or can run queries for data that he is otherwise not supposed to.
  • Privilege Abuse
    An adversary is able to exploit features of the target that should be reserved for privileged users or administrators but are exposed to use by lower or non-privileged accounts. Access to sensitive information and functionality must be controlled to ensure that only authorized users are able to access these resources. If access control mechanisms are absent or misconfigured, a user may be able to access resources that are intended only for higher level users. An adversary may be able to exploit this to utilize a less trusted account to gain information and perform activities reserved for more trusted accounts. This attack differs from privilege escalation and other privilege stealing attacks in that the adversary never actually escalates their privileges but instead is able to use a lesser degree of privilege to access resources that should be (but are not) reserved for higher privilege accounts. Likewise, the adversary does not exploit trust or subvert systems - all control functionality is working as configured but the configuration does not adequately protect sensitive resources at an appropriate level.
  • Directory Indexing
    An adversary crafts a request to a target that results in the target listing/indexing the content of a directory as output. One common method of triggering directory contents as output is to construct a request containing a path that terminates in a directory name rather than a file name since many applications are configured to provide a list of the directory's contents when such a request is received. An adversary can use this to explore the directory tree on a target as well as learn the names of files. This can often end up revealing test files, backup files, temporary files, hidden files, configuration files, user accounts, script contents, as well as naming conventions, all of which can be used by an attacker to mount additional attacks.
  • 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.
  • Exploiting Incorrectly Configured Access Control Security Levels
    An attacker exploits a weakness in the configuration of access controls and is able to bypass the intended protection that these measures guard against and thereby obtain unauthorized access to the system or network. Sensitive functionality should always be protected with access controls. However configuring all but the most trivial access control systems can be very complicated and there are many opportunities for mistakes. If an attacker can learn of incorrectly configured access security settings, they may be able to exploit this in an attack. Most commonly, attackers would take advantage of controls that provided too little protection for sensitive activities in order to perform actions that should be denied to them. In some circumstances, an attacker may be able to take advantage of overly restrictive access control policies, initiating denial of services (if an application locks because it unexpectedly failed to be granted access) or causing other legitimate actions to fail due to security. The latter class of attacks, however, is usually less severe and easier to detect than attacks based on inadequate security restrictions. This attack pattern differs from CAPEC 1, "Accessing Functionality Not Properly Constrained by ACLs" in that the latter describes attacks where sensitive functionality lacks access controls, where, in this pattern, the access control is present, but incorrectly configured.

Nessus

  • NASL familyDebian Local Security Checks
    NASL idDEBIAN_DSA-3895.NASL
    descriptionIt was discovered that Flatpak, an application deployment framework for desktop apps insufficiently restricted file permissinons in third-party repositories, which could result in privilege escalation.
    last seen2020-06-01
    modified2020-06-02
    plugin id101012
    published2017-06-23
    reporterThis script is Copyright (C) 2017-2018 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101012
    titleDebian DSA-3895-1 : flatpak - security update
    code
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from Debian Security Advisory DSA-3895. The text 
    # itself is copyright (C) Software in the Public Interest, Inc.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(101012);
      script_version("3.7");
      script_cvs_date("Date: 2018/11/10 11:49:38");
    
      script_cve_id("CVE-2017-9780");
      script_xref(name:"DSA", value:"3895");
    
      script_name(english:"Debian DSA-3895-1 : flatpak - 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:
    "It was discovered that Flatpak, an application deployment framework
    for desktop apps insufficiently restricted file permissinons in
    third-party repositories, which could result in privilege escalation."
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://packages.debian.org/source/stretch/flatpak"
      );
      script_set_attribute(
        attribute:"see_also",
        value:"https://www.debian.org/security/2017/dsa-3895"
      );
      script_set_attribute(
        attribute:"solution", 
        value:
    "Upgrade the flatpak packages.
    
    For the stable distribution (stretch), this problem has been fixed in
    version 0.8.5-2+deb9u1."
      );
      script_set_cvss_base_vector("CVSS2#AV:L/AC:L/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:L/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:"exploitability_ease", value:"No known exploits are available");
      script_set_attribute(attribute:"exploit_available", value:"false");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:flatpak");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:9.0");
    
      script_set_attribute(attribute:"patch_publication_date", value:"2017/06/22");
      script_set_attribute(attribute:"plugin_publication_date", value:"2017/06/23");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2017-2018 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:"9.0", prefix:"flatpak", reference:"0.8.5-2+deb9u1")) flag++;
    if (deb_check(release:"9.0", prefix:"flatpak-builder", reference:"0.8.5-2+deb9u1")) flag++;
    if (deb_check(release:"9.0", prefix:"flatpak-tests", reference:"0.8.5-2+deb9u1")) flag++;
    if (deb_check(release:"9.0", prefix:"gir1.2-flatpak-1.0", reference:"0.8.5-2+deb9u1")) flag++;
    if (deb_check(release:"9.0", prefix:"libflatpak-dev", reference:"0.8.5-2+deb9u1")) flag++;
    if (deb_check(release:"9.0", prefix:"libflatpak-doc", reference:"0.8.5-2+deb9u1")) flag++;
    if (deb_check(release:"9.0", prefix:"libflatpak0", reference:"0.8.5-2+deb9u1")) 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 familyFedora Local Security Checks
    NASL idFEDORA_2017-6B1F07ACD9.NASL
    descriptionSecurity fix for CVE-2017-9780 Update to 0.8.7 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen2020-06-05
    modified2017-07-13
    plugin id101505
    published2017-07-13
    reporterThis script is Copyright (C) 2017-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101505
    titleFedora 24 : flatpak (2017-6b1f07acd9)
    code
    #%NASL_MIN_LEVEL 80502
    #
    # (C) Tenable Network Security, Inc.
    #
    # The descriptive text and package checks in this plugin were  
    # extracted from Fedora Security Advisory FEDORA-2017-6b1f07acd9.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(101505);
      script_version("3.4");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/04");
    
      script_cve_id("CVE-2017-9780");
      script_xref(name:"FEDORA", value:"2017-6b1f07acd9");
    
      script_name(english:"Fedora 24 : flatpak (2017-6b1f07acd9)");
      script_summary(english:"Checks rpm output for the updated package.");
    
      script_set_attribute(
        attribute:"synopsis", 
        value:"The remote Fedora host is missing a security update."
      );
      script_set_attribute(
        attribute:"description", 
        value:
    "Security fix for CVE-2017-9780
    
    Update to 0.8.7
    
    Note that Tenable Network Security has extracted the preceding
    description block directly from the Fedora update system website.
    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://bodhi.fedoraproject.org/updates/FEDORA-2017-6b1f07acd9"
      );
      script_set_attribute(
        attribute:"solution", 
        value:"Update the affected flatpak package."
      );
      script_set_cvss_base_vector("CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C");
      script_set_cvss3_base_vector("CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H");
    
      script_set_attribute(attribute:"plugin_type", value:"local");
      script_set_attribute(attribute:"cpe", value:"p-cpe:/a:fedoraproject:fedora:flatpak");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:24");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2017/06/21");
      script_set_attribute(attribute:"patch_publication_date", value:"2017/07/11");
      script_set_attribute(attribute:"plugin_publication_date", value:"2017/07/13");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_end_attributes();
    
      script_category(ACT_GATHER_INFO);
      script_copyright(english:"This script is Copyright (C) 2017-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
      script_family(english:"Fedora Local Security Checks");
    
      script_dependencies("ssh_get_info.nasl");
      script_require_keys("Host/local_checks_enabled", "Host/RedHat/release", "Host/RedHat/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/RedHat/release");
    if (isnull(release) || "Fedora" >!< release) audit(AUDIT_OS_NOT, "Fedora");
    os_ver = pregmatch(pattern: "Fedora.*release ([0-9]+)", string:release);
    if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Fedora");
    os_ver = os_ver[1];
    if (! preg(pattern:"^24([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 24", "Fedora " + os_ver);
    
    if (!get_kb_item("Host/RedHat/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, "Fedora", cpu);
    
    
    flag = 0;
    if (rpm_check(release:"FC24", reference:"flatpak-0.8.7-1.fc24")) 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, "flatpak");
    }
    
  • NASL familySuSE Local Security Checks
    NASL idOPENSUSE-2018-139.NASL
    descriptionThis update for flatpak to version 0.8.9 fixes security issues and bugs. The following vulnerabilities were fixed : - CVE-2018-6560: sandbox escape in the flatpak dbus proxy (boo#1078923) - CVE-2017-9780: Malicious apps could have included inappropriate permissions (boo#1078989) - old-style eavesdropping in the dbus proxy (boo#1078993) This update also includes all upstream improvements and fixes in this stable release series.
    last seen2020-06-05
    modified2018-02-08
    plugin id106663
    published2018-02-08
    reporterThis script is Copyright (C) 2018-2020 Tenable Network Security, Inc.
    sourcehttps://www.tenable.com/plugins/nessus/106663
    titleopenSUSE Security Update : flatpak (openSUSE-2018-139)