Detections
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Amazon Linux AMI : cacti (ALAS-2023-1675)
critical Nessus Plugin ID 170545
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Synopsis
The remote Amazon Linux AMI host is missing a security update.Description
The version of cacti installed on the remote host is prior to 1.1.19-2.20. It is, therefore, affected by a vulnerability as referenced in the ALAS-2023-1675 advisory.- 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. (CVE-2022-46169)
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
Solution
Run 'yum update cacti' to update your system.See Also
Plugin Details
Severity: Critical
ID: 170545
File Name: ala_ALAS-2023-1675.nasl
Version: 1.3
Type: local
Agent: unix
Published: 1/24/2023
Updated: 9/6/2023
Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus
Risk Information
VPR
Risk Factor: High
Score: 7.4
CVSS v2
Risk Factor: Critical
Base Score: 10
Temporal Score: 8.7
Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C
CVSS Score Source: CVE-2022-46169
CVSS v3
Risk Factor: Critical
Base Score: 9.8
Temporal Score: 9.4
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Temporal Vector: CVSS:3.0/E:H/RL:O/RC:C
Vulnerability Information
CPE: p-cpe:/a:amazon:linux:cacti, cpe:/o:amazon:linux
Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list
Exploit Available: true
Exploit Ease: Exploits are available
Patch Publication Date: 1/19/2023
Vulnerability Publication Date: 12/5/2022
CISA Known Exploited Vulnerability Due Dates: 3/9/2023
Exploitable With
Core Impact
Metasploit (Cacti 1.2.22 unauthenticated command injection)
Reference Information
CVE: CVE-2022-46169