Vulnerabilities > CVE-2017-10923 - Improper Input Validation vulnerability in XEN

047910
CVSS 6.5 - MEDIUM
Attack vector
NETWORK
Attack complexity
LOW
Privileges required
LOW
Confidentiality impact
NONE
Integrity impact
NONE
Availability impact
HIGH
network
low complexity
xen
CWE-20
nessus

Summary

Xen through 4.8.x does not validate a vCPU array index upon the sending of an SGI, which allows guest OS users to cause a denial of service (hypervisor crash), aka XSA-225.

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 familyFedora Local Security Checks
    NASL idFEDORA_2017-C3149B5FCB.NASL
    descriptionxen: various flaws (#1463247) blkif responses leak backend stack data [XSA-216] page transfer may allow PV guest to elevate privilege [XSA-217] Races in the grant table unmap code [XSA-218] x86: insufficient reference counts during shadow emulation [XSA-219] x86: PKRU and BND* leakage between vCPU-s [XSA-220] stale P2M mappings due to insufficient error checking [XSA-222] ARM guest disabling interrupt may crash Xen [XSA-223] grant table operations mishandle reference counts [XSA-224] arm: vgic: Out-of-bound access when sending SGIs [XSA-225] NULL pointer deref in event channel poll [XSA-221] (#1463231) 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
    modified2017-06-23
    plugin id101028
    published2017-06-23
    reporterThis script is Copyright (C) 2017-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101028
    titleFedora 25 : xen (2017-c3149b5fcb)
    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-c3149b5fcb.
    #
    
    include("compat.inc");
    
    if (description)
    {
      script_id(101028);
      script_version("1.7");
      script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/04");
    
      script_cve_id("CVE-2017-10911", "CVE-2017-10912", "CVE-2017-10913", "CVE-2017-10915", "CVE-2017-10916", "CVE-2017-10917", "CVE-2017-10918", "CVE-2017-10919", "CVE-2017-10920", "CVE-2017-10923");
      script_xref(name:"FEDORA", value:"2017-c3149b5fcb");
      script_xref(name:"IAVB", value:"2017-B-0074");
    
      script_name(english:"Fedora 25 : xen (2017-c3149b5fcb)");
      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:
    "xen: various flaws (#1463247) blkif responses leak backend stack data
    [XSA-216] page transfer may allow PV guest to elevate privilege
    [XSA-217] Races in the grant table unmap code [XSA-218] x86:
    insufficient reference counts during shadow emulation [XSA-219] x86:
    PKRU and BND* leakage between vCPU-s [XSA-220] stale P2M mappings due
    to insufficient error checking [XSA-222] ARM guest disabling interrupt
    may crash Xen [XSA-223] grant table operations mishandle reference
    counts [XSA-224] arm: vgic: Out-of-bound access when sending SGIs
    [XSA-225] NULL pointer deref in event channel poll [XSA-221]
    (#1463231)
    
    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-c3149b5fcb"
      );
      script_set_attribute(attribute:"solution", value:"Update the affected xen package.");
      script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C");
      script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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:xen");
      script_set_attribute(attribute:"cpe", value:"cpe:/o:fedoraproject:fedora:25");
    
      script_set_attribute(attribute:"vuln_publication_date", value:"2017/07/05");
      script_set_attribute(attribute:"patch_publication_date", value:"2017/07/11");
      script_set_attribute(attribute:"plugin_publication_date", value:"2017/06/23");
      script_set_attribute(attribute:"generated_plugin", value:"current");
      script_set_attribute(attribute:"stig_severity", value:"I");
      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:"^25([^0-9]|$)", string:os_ver)) audit(AUDIT_OS_NOT, "Fedora 25", "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:"FC25", reference:"xen-4.7.2-7.fc25")) 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, "xen");
    }
    
  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2017-5C6A9B07A3.NASL
    descriptionxen: various flaws (#1463247) blkif responses leak backend stack data [XSA-216] page transfer may allow PV guest to elevate privilege [XSA-217] Races in the grant table unmap code [XSA-218] x86: insufficient reference counts during shadow emulation [XSA-219] x86: PKRU and BND* leakage between vCPU-s [XSA-220] NULL pointer deref in event channel poll [XSA-221] (#1463231) stale P2M mappings due to insufficient error checking [XSA-222] ARM guest disabling interrupt may crash Xen [XSA-223] grant table operations mishandle reference counts [XSA-224] arm: vgic: Out-of-bound access when sending SGIs [XSA-225] 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
    modified2017-07-17
    plugin id101638
    published2017-07-17
    reporterThis script is Copyright (C) 2017-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101638
    titleFedora 26 : xen (2017-5c6a9b07a3)
  • NASL familyFedora Local Security Checks
    NASL idFEDORA_2017-B3BDAF58BC.NASL
    descriptionxen: various flaws (#1463247) blkif responses leak backend stack data [XSA-216] page transfer may allow PV guest to elevate privilege [XSA-217] Races in the grant table unmap code [XSA-218] x86: insufficient reference counts during shadow emulation [XSA-219] x86: PKRU and BND* leakage between vCPU-s [XSA-220] stale P2M mappings due to insufficient error checking [XSA-222] ARM guest disabling interrupt may crash Xen [XSA-223] grant table operations mishandle reference counts [XSA-224] arm: vgic: Out-of-bound access when sending SGIs [XSA-225] NULL pointer deref in event channel poll [XSA-221] (#1463231) 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
    modified2017-07-03
    plugin id101183
    published2017-07-03
    reporterThis script is Copyright (C) 2017-2020 and is owned by Tenable, Inc. or an Affiliate thereof.
    sourcehttps://www.tenable.com/plugins/nessus/101183
    titleFedora 24 : xen (2017-b3bdaf58bc)