CVE-2019-18425 (GCVE-0-2019-18425)

Vulnerability from cvelistv5 – Published: 2019-10-31 13:39 – Updated: 2024-08-05 01:54
VLAI?
Summary
An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don't install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected.
Severity ?
No CVSS data available.
CWE
  • n/a
Assigner
References
URL Tags
http://xenbits.xen.org/xsa/advisory-298.html x_refsource_MISC
http://www.openwall.com/lists/oss-security/2019/10/31/2 mailing-listx_refsource_MLIST
http://lists.opensuse.org/opensuse-security-annou… vendor-advisoryx_refsource_SUSE
https://lists.fedoraproject.org/archives/list/pac… vendor-advisoryx_refsource_FEDORA
https://lists.fedoraproject.org/archives/list/pac… vendor-advisoryx_refsource_FEDORA
https://lists.fedoraproject.org/archives/list/pac… vendor-advisoryx_refsource_FEDORA
https://www.debian.org/security/2020/dsa-4602 vendor-advisoryx_refsource_DEBIAN
https://seclists.org/bugtraq/2020/Jan/21 mailing-listx_refsource_BUGTRAQ
https://security.gentoo.org/glsa/202003-56 vendor-advisoryx_refsource_GENTOO
Show details on NVD website
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    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2019-18425\",\"sourceIdentifier\":\"cve@mitre.org\",\"published\":\"2019-10-31T14:15:12.150\",\"lastModified\":\"2024-11-21T04:33:14.447\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"An issue was discovered in Xen through 4.12.x allowing 32-bit PV guest OS users to gain guest OS privileges by installing and using descriptors. There is missing descriptor table limit checking in x86 PV emulation. When emulating certain PV guest operations, descriptor table accesses are performed by the emulating code. Such accesses should respect the guest specified limits, unless otherwise guaranteed to fail in such a case. Without this, emulation of 32-bit guest user mode calls through call gates would allow guest user mode to install and then use descriptors of their choice, as long as the guest kernel did not itself install an LDT. (Most OSes don\u0027t install any LDT by default). 32-bit PV guest user mode can elevate its privileges to that of the guest kernel. Xen versions from at least 3.2 onwards are affected. Only 32-bit PV guest user mode can leverage this vulnerability. HVM, PVH, as well as 64-bit PV guests cannot leverage this vulnerability. Arm systems are unaffected.\"},{\"lang\":\"es\",\"value\":\"Se detect\u00f3 un problema en Xen versiones hasta 4.12.x, permitiendo a usuarios del SO invitado de PV de 32 bits alcanzar privilegios del SO invitado mediante la instalaci\u00f3n y el uso de descriptores. Se presenta una falta la comprobaci\u00f3n de l\u00edmite de la tabla descriptor en la emulaci\u00f3n PV x86. Al emular determinadas operaciones de invitados PV, el c\u00f3digo de emulaci\u00f3n realiza los accesos a la tabla de descriptores. Dichos accesos deben respetar los l\u00edmites especificados por parte del invitado, a menos que se garantice que fallen en tal caso. Sin esto, la emulaci\u00f3n de llamadas de modo de usuario invitado de 32 bits por medio de las puertas de llamada permitir\u00eda la instalaci\u00f3n del modo de usuario invitado y luego usar\u00eda los descriptores de su elecci\u00f3n, siempre que el kernel invitado no instalara un LDT. (La mayor\u00eda de los sistemas operativos no instalan ning\u00fan LDT por defecto). El modo de usuario invitado PV de 32 bits puede elevar sus privilegios a los del kernel invitado. Las versiones de Xen de por lo menos 3.2 en adelante est\u00e1n afectadas. Solo el modo de usuario invitado PV de 32 bits puede aprovechar esta vulnerabilidad. HVM, PVH, as\u00ed como los invitados PV de 64 bits no pueden explotar esta vulnerabilidad. Los sistemas ARM no est\u00e1n afectados.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}],\"cvssMetricV2\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"2.0\",\"vectorString\":\"AV:N/AC:M/Au:N/C:C/I:C/A:C\",\"baseScore\":9.3,\"accessVector\":\"NETWORK\",\"accessComplexity\":\"MEDIUM\",\"authentication\":\"NONE\",\"confidentialityImpact\":\"COMPLETE\",\"integrityImpact\":\"COMPLETE\",\"availabilityImpact\":\"COMPLETE\"},\"baseSeverity\":\"HIGH\",\"exploitabilityScore\":8.6,\"impactScore\":10.0,\"acInsufInfo\":false,\"obtainAllPrivilege\":false,\"obtainUserPrivilege\":false,\"obtainOtherPrivilege\":false,\"userInteractionRequired\":false}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-269\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:xen:xen:*:*:*:*:*:*:x86:*\",\"versionEndIncluding\":\"4.12.1\",\"matchCriteriaId\":\"18F9F58D-58A0-4356-AB70-E5ACF913BFCA\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"DEECE5FC-CACF-4496-A3E7-164736409252\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"07B237A9-69A3-4A9C-9DA0-4E06BD37AE73\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"D100F7CE-FC64-4CC6-852A-6136D72DA419\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"97A4B8DF-58DA-4AB6-A1F9-331B36409BA3\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"80F0FA5D-8D3B-4C0E-81E2-87998286AF33\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:opensuse:leap:15.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"F1E78106-58E6-4D59-990F-75DA575BFAD9\"}]}]}],\"references\":[{\"url\":\"http://lists.opensuse.org/opensuse-security-announce/2019-11/msg00037.html\",\"source\":\"cve@mitre.org\",\"tags\":[\"Mailing 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Advisory\"]},{\"url\":\"https://www.debian.org/security/2020/dsa-4602\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]}]}}"
  }
}


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Tags
Taxonomy of the tags.




Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.