What is file upload:
Some web applications allow uploading pictures, text or other resources to a specified location. The file upload vulnerability is to use these places that can be uploaded to implant malicious code into the server, and then access it through the url to execute the code.
WebShell
is a command interpreter that communicates via the Web, also known as a website backdoor.
In essence, WebShell is a file that can execute script commands, and its form can be of any type.
Why is there a loophole in file uploading?
When uploading files, if the server script language does not strictly verify and filter the uploaded files, it is easy to Causes the upload of arbitrary files, including upload script files.
If it is a normal PHP file, there is no harm to the server.
Like other programming languages, PHP can view files in a directory, view the contents of files, and execute system commands.
* When uploading files, if the server-side scripting language does not strictly verify and filter the uploaded files, it is possible to upload malicious PHP files to control the entire website, even the server. This malicious PHP file is also known as WebShell.
Where is the file upload vulnerability?
The server is improperly configured
. The upload vulnerability of the open source editor. The
local file upload restriction is bypassed , the
filtering is not strict, or the
file parsing vulnerability is
bypassed . detect
Detect file content,
set upload whitelist
Some web applications allow uploading pictures, text or other resources to a specified location. The file upload vulnerability is to use these places that can be uploaded to implant malicious code into the server, and then access it through the url to execute the code.
WebShell
is a command interpreter that communicates via the Web, also known as a website backdoor.
In essence, WebShell is a file that can execute script commands, and its form can be of any type.
Why is there a loophole in file uploading?
When uploading files, if the server script language does not strictly verify and filter the uploaded files, it is easy to Causes the upload of arbitrary files, including upload script files.
If it is a normal PHP file, there is no harm to the server.
Like other programming languages, PHP can view files in a directory, view the contents of files, and execute system commands.
* When uploading files, if the server-side scripting language does not strictly verify and filter the uploaded files, it is possible to upload malicious PHP files to control the entire website, even the server. This malicious PHP file is also known as WebShell.
Where is the file upload vulnerability?
The server is improperly configured
. The upload vulnerability of the open source editor. The
local file upload restriction is bypassed , the
filtering is not strict, or the
file parsing vulnerability is
bypassed . detect
Detect file content,
set upload whitelist