CVE-2017-0160 : Detail

CVE-2017-0160

7.8
/
High
7.58%V3
Local
2017-04-12
12h00 +00:00
2017-08-15
07h57 +00:00
CVE.org
NVD
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CVE Descriptions

Microsoft .NET Framework 2.0, 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2 and 4.7 allows an attacker with access to the local system to execute malicious code, aka ".NET Remote Code Execution Vulnerability."

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE Other No informations.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 7.8 HIGH CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

Local

A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file.

Attack Complexity

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

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.

Privileges Required

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

Low

The attacker is authorized with (i.e. requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.

User Interaction

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

None

The vulnerable system can be exploited without interaction from any user.

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.

High

There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

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.

High

There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

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 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 41903

Publication date : 2017-04-19 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=1081 Windows: ManagementObject Arbitrary .NET Serialization RCE Platform: .NET 4.6, Powershell 4. Tested between Server 2016 and Windows 10 Anniversary Edition Class: Remote Code Execution Summary: Accessing a compromised WMI server over DCOM using System.Management classes or the Powershell Get-WmiObject Cmdlet can lead to the server running arbitrary code on the calling machine leading to RCE. Description: The dangers of using .NET for DCOM are well know, the SRD blog made a post (https://blogs.technet.microsoft.com/srd/2014/10/14/more-details-about-cve-2014-4073-elevation-of-privilege-vulnerability/) which explicitly said it shouldn’t be used between trust boundaries. Presumably people took this to mean implementing servers, but it’s also a risk if a .NET DCOM client connects to an untrusted endpoint. This is due to the IManagedObject interface which will automatically force a client to deserialize an untrusted BinaryFormatter stream which is known bad. One common use of DCOM in the .NET framework is for WMI access. The old classes in the System.Management namespace are still accessible (even though technically supersceded by Cim classes) and in powershell they act as the backend for Get-WmiObject and family. Through inspection it’s clear that a number of places the client querys for IManagedObject (for example on the IWbemServices object returned from IWbemLevel1Login::NTLMLogin method) and would be vulnerable. If this interface is being queried it means that a .NET client is trying to create an RCW and will try and create a local copy of a remote serializable object. Therefore in corporate scenarios where some central system is using WMI over DCOM for management and analysis of running systems (and the management code is using the old .NET/PS classes to do the calls) a compromised machine which replaces the WMI service with its own malicious one could get arbitrary code execution on the monitoring machine. As this is typically going to be a higher privileged account (due to the requirements of DCOM access) it probably makes it more serious. Looking at the network traffic the initial CreateInstance call on the remote activator is only using CONNECT level authentication. This means that it might also be possible to MITM (or Man-At-The-Side) a .NET WMI client and send it back a malicious COM objref to get it to communicate with the attacker's server. Of course ideally no one would do this, or use the old style .NET and PS commands. But I’m sure there are networks out there which do so. Proof of Concept: I’ve provided a PoC as a C# project. You’ll need to also set up some machines to test this out. I’ve tested it in a simple environment of a Server 2016 server acting as a DC and a Windows 10 client. The serialized stream is tailored specifically for 4.6, I don’t know if it works anywhere else. 1) Compile the C# project and copy the binary to c:\service\FakeWmiServer.exe on the Client machine. 2) Run the following commands in admin Powershell on the client machine to configure the WMI service and add the server executable to the firewall. New-NetFirewallRule -DisplayName FAKEWMI -Enabled True -Profile Any -Direction Inbound -Program C:\service\FakeWMIService.exe -Protocol Tcp -LocalPort Any -RemotePort Any -LocalAddress Any -RemoteAddress Any New-NetFirewallRule -DisplayName FAKEWMI -Enabled True -Profile Any -Direction Outbound -Program C:\service\FakeWMIService.exe -Protocol Tcp -LocalPort Any -RemotePort Any -LocalAddress Any -RemoteAddress Any sc.exe config winmgmt binPath= c:\service\FakeWMIService.exe type= own Restart-Service winmgmt -Force 3) On the server start powershell. 4) On the server execute the PS command “Get-WmiObject -Class Win32_Process -ComputerName hostname” replacing hostname with the address of the client. Expected Result: WMI connection fails. Observed Result: A copy of CMD and Notepad is executed on the server in the context of the calling user. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/41903.zip

Products Mentioned

Configuraton 0

Microsoft>>.net_framework >> Version 2.0

Microsoft>>.net_framework >> Version 3.5

Microsoft>>.net_framework >> Version 3.5.1

Microsoft>>.net_framework >> Version 4.5.2

Microsoft>>.net_framework >> Version 4.6

Microsoft>>.net_framework >> Version 4.6.1

Microsoft>>.net_framework >> Version 4.6.2

Microsoft>>.net_framework >> Version 4.7

References

http://www.securityfocus.com/bid/97447
Tags : vdb-entry, x_refsource_BID
https://www.exploit-db.com/exploits/41903/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securitytracker.com/id/1038236
Tags : vdb-entry, x_refsource_SECTRACK