Very High
CVE-2022-46169
CVE ID
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CVE-2022-46169
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
Cacti is an open source platform which provides a robust and extensible operational monitoring and fault management framework for users. In affected versions a command injection vulnerability allows an unauthenticated user to execute arbitrary code on a server running Cacti, if a specific data source was selected for any monitored device. The vulnerability resides in the remote_agent.php
file. This file can be accessed without authentication. This function retrieves the IP address of the client via get_client_addr
and resolves this IP address to the corresponding hostname via gethostbyaddr
. After this, it is verified that an entry within the poller
table exists, where the hostname corresponds to the resolved hostname. If such an entry was found, the function returns true
and the client is authorized. This authorization can be bypassed due to the implementation of the get_client_addr
function. The function is defined in the file lib/functions.php
and checks serval $_SERVER
variables to determine the IP address of the client. The variables beginning with HTTP_
can be arbitrarily set by an attacker. Since there is a default entry in the poller
table with the hostname of the server running Cacti, an attacker can bypass the authentication e.g. by providing the header Forwarded-For: <TARGETIP>
. This way the function get_client_addr
returns the IP address of the server running Cacti. The following call to gethostbyaddr
will resolve this IP address to the hostname of the server, which will pass the poller
hostname check because of the default entry. After the authorization of the remote_agent.php
file is bypassed, an attacker can trigger different actions. One of these actions is called polldata
. The called function poll_for_data
retrieves a few request parameters and loads the corresponding poller_item
entries from the database. If the action
of a poller_item
equals POLLER_ACTION_SCRIPT_PHP
, the function proc_open
is used to execute a PHP script. The attacker-controlled parameter $poller_id
is retrieved via the function get_nfilter_request_var
, which allows arbitrary strings. This variable is later inserted into the string passed to proc_open
, which leads to a command injection vulnerability. By e.g. providing the poller_id=;id
the id
command is executed. In order to reach the vulnerable call, the attacker must provide a host_id
and local_data_id
, where the action
of the corresponding poller_item
is set to POLLER_ACTION_SCRIPT_PHP
. Both of these ids (host_id
and local_data_id
) can easily be bruteforced. The only requirement is that a poller_item
with an POLLER_ACTION_SCRIPT_PHP
action exists. This is very likely on a productive instance because this action is added by some predefined templates like Device - Uptime
or Device - Polling Time
.
This command injection vulnerability allows an unauthenticated user to execute arbitrary commands if a poller_item
with the action
type POLLER_ACTION_SCRIPT_PHP
(2
) is configured. The authorization bypass should be prevented by not allowing an attacker to make get_client_addr
(file lib/functions.php
) return an arbitrary IP address. This could be done by not honoring the HTTP_...
$_SERVER
variables. If these should be kept for compatibility reasons it should at least be prevented to fake the IP address of the server running Cacti. This vulnerability has been addressed in both the 1.2.x and 1.3.x release branches with 1.2.23
being the first release containing the patch.
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Ratings
-
Attacker ValueVery High
-
ExploitabilityHigh
Technical Analysis
Rating this vulnerability as high in terms of attacker value. The command injection vulnerability seems relatively trivial to exploit, and it grants an attacker unauthenticated remote code execution as the user running the Cacti service.
If an attacker sends a GET request to remote_agent.php
with the action set to polldata
, it is possible to reach a code path that calls the php function proc_open()
on unsanitized, attacker-controlled data. Specifically, the poller_id
parameter in the request permits strings as valid input. To reach this code path, the Cacti server must have a poller item with the POLLER_ACTION_SCRIPT_PHP
action, and the local_data_ids[0]
and host_id
parameters must be valid ids associated with a poller item in the database. According to one of the researchers who discovered this vulnerability, the POLLER_ACTION_SCRIPT_PHP
action should be common in production since many of the default templates used to create a poller item have this action enabled. Additionally, supplying valid ids for the local_data_ids[0]
and host_id
parameters should be trivial, as they can be bruteforced.
There is currently a Metasploit module in flight for this vulnerability.
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General Information
Vendors
- cacti
Products
- cacti
Exploited in the Wild
- Vendor Advisory (https://github.com/Cacti/cacti/security/advisories/GHSA-6p93-p743-35gf)
- Government or Industry Alert (https://www.cisa.gov/known-exploited-vulnerabilities-catalog)
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Exploit
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Additional Info
Technical Analysis
Report as Exploited in the Wild
CVE ID
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