CVE-2019-0612 : Détail

CVE-2019-0612

5.3
/
Moyen
10.1%V4
Network
2019-04-08
20h34 +00:00
2019-04-08
20h34 +00:00
CVE.org
NVD
Notifications pour un CVE
Restez informé de toutes modifications pour un CVE spécifique.
Gestion des notifications

Descriptions du CVE

A security feature bypass vulnerability exists when Click2Play protection in Microsoft Edge improperly handles flash objects. By itself, this bypass vulnerability does not allow arbitrary code execution, aka 'Microsoft Edge Security Feature Bypass Vulnerability'.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE Other No informations.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.0 5.3 MEDIUM CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from routers).

Attack Complexity

This metric describes the conditions beyond the attacker's control that must exist in order to exploit the vulnerability.

High

A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.

User Interaction

This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise of the vulnerable component.

Required

Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator.

Base: Scope Metrics

An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges.

Scope

Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports.

Unchanged

An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same.

Base: Impact Metrics

The Impact metrics refer to the properties of the impacted component.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

None

There is no loss of confidentiality within the impacted component.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

None

There is no impact to availability within the impacted component.

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence that one has in the description of a vulnerability.

Environmental Metrics

 nvd@nist.gov
V2 2.6 AV:N/AC:H/Au:N/C:N/I:P/A:N nvd@nist.gov

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 46569

Date de publication : 2019-03-18 23h00 +00:00
Auteur : Google Security Research
EDB Vérifié : Yes

Attached is a PoC file that bypasses Flash click2play in Microsoft Edge. This was tested on Windows 10 64bit v 1809 with the latest patches applied. The PoC currently loads a swf from wwwimages.adobe.com (screenshot attached), but can load a swf from any domain and also the PoC itself can be hosted on any domain. Note that there is a race condition wrt displaying the loaded Flash object, so if you run the PoC and don't see anything after several seconds, please refresh the page or load the PoC again. However, it worked pretty reliably in my experiments. To see how it works, let's first examine the CObjectElement::FinalCreateObject, which gets called eventually after a new <object> element is created. The code relevant for this vulnerability is: int CObjectElement::FinalCreateObject(...) { CLSID clsid; ... RetrieveClassidAndData(..., &clsid, ...) ... if(!COleSite::AllowCreate(this, clsid, ...)) { OnFailToCreate(); return 0x80070005; } ... if(clsid == CLSID_MacromediaSwFlash && CDOMPluginArray::IsFlashCreateable(...)) { ... CView::AddPendingSizeDeterminationOleSite(...) } else { COleSite::CreateObject(this, clsid); } ... } Looking at the line if(clsid == CLSID_MacromediaSwFlash && CDOMPluginArray::IsFlashCreateable(...)) you can see that if clsid is Flash clsid and if IsFlashCreateable() returns true, the Flash object will be loaded at a later time. This happens in COleSite::ProcessObjectAfterSizeDetermined after checking if either the user explicitly allowed Flash for this site, or if the site is "trusted by platform". This is how Flash objects are normally loaded. However, in the opposite case, if clsid != CLSID_MacromediaSwFlash *or* if IsFlashCreateable() returns false (regardless of the clsid), COleSite::CreateObject is called, which creates the object immediately without performing any additional checks. Essentially the logic here in case of clsid == CLSID_MacromediaSwFlash is "If Flash isn't creatable, create the Flash object anyway", which is a bit strange and which is what the PoC exploits. However, exercising this path is not trivial because of the earlier AllowCreate() check. AllowCreate() and IsFlashCreateable() perform very similar checks - they both eventually call COleSite::AllowCreateSecurityChecks. This means that in most of the cases where IsFlashCreateable() returns false, AllowCreate() returns false as well. In most cases, but not all :-) Specifically, in COleSite::AllowCreate, if the current <object> element does not have an associated Markup (is not a part of any element tree), then AllowCreate() calls COleSite::AllowCreateSecurityChecks() with the 4th argument set to 0. This has the effect that most checks will be skipped and AllowCreate() will return true (almost) always. Now we just need to make CDOMPluginArray::IsFlashCreateable return false, and in the PoC this is done by making the associated document of the current <object> element a "dynamic" document. This way, COleSite::CreateObject is called without click2play checks. However, if we leave a PoC at this stage, there is going to be a (non-fatal) exception in communication between the Content Process and the Plugin Process. I'm not sure if this happens before or after the Flash object is actually loaded. In any case, we can avoid this by quickly putting the <object> element into a "normal" document tree. This also causes the Flash object to be shown on the page normally, for a dramatic effect :-) Please also note that most of the logic shown above for CObjectElement::FinalCreateObject is also present in CPluginSite::FinishCreateObject, which is used for handling for example <embed> elements. While the current PoC does not work on <embed> elements as is, it might be possible to make it work with some modifications. So, when fixing CObjectElement::FinalCreateObject, please remember to also address CPluginSite::FinishCreateObject. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/46569.zip

Products Mentioned

Configuraton 0

Microsoft>>Edge >> Version -

Microsoft>>Windows_10 >> Version 1703

Microsoft>>Windows_10 >> Version 1709

Microsoft>>Windows_10 >> Version 1803

Microsoft>>Windows_10 >> Version 1809

Microsoft>>Windows_server_2019 >> Version -

Références

Les informations affichées sur CVE Find proviennent de plusieurs sources de référence rigoureusement sélectionnées. Les données CVE sont fournies par MITRE Corporation et la National Vulnerability Database (NVD). Le catalogue des vulnérabilités activement exploitées (KEV) provient de la Cybersecurity and Infrastructure Security Agency (CISA), tandis que les scores EPSS sont issus de FIRST.org. Enfin, les données relatives aux faiblesses logicielles (CWE) et aux schémas d'attaque courants (CAPEC) sont maintenues par MITRE Corporation, et les informations sur les configurations logicielles et matérielles (CPE) proviennent du NVD.