How to execute binary executable using wget

redss · 06-09-2009, 04:15 PM

I can locally execute a shell script that resides on a webserver by piping the script to sh, with the following command:

Code:

wget www.somewhere.com/somefile.sh -O - | sh

Now how can I execute a BINARY executable that resides on a webserver?

Valery Reznic · 06-10-2009, 01:21 AM

Quote:

Originally Posted by redss

I can locally execute a shell script that resides on a webserver by piping the script to sh, with the following command:

Code:

wget www.somewhere.com/somefile.sh -O - | sh

Now how can I execute a BINARY executable that resides on a webserver?

What wrong with

Code:

wget www.somewhere.com/somefile.exe
chnod 755 somefile.exe
./somefile.exe

redss · 06-10-2009, 12:16 PM

That would work, but it's 3 lines as opposed to one line. And the same filename has to be redundantly used 3 times. If there's a way to do it with one command, I want to do it that way, it would look cleaner :-)

Valery Reznic · 06-11-2009, 01:27 AM

Quote:

Originally Posted by redss

That would work, but it's 3 lines as opposed to one line. And the same filename has to be redundantly used 3 times. If there's a way to do it with one command, I want to do it that way, it would look cleaner :-)

Put it in the script.

Code:

#!/bin/sh
[ $# -ne 1 -o "x$1" = "x" ] && {
   echo "Usage: $0 <url>" 1>&2
   exit 1
}
url=$1
filename=`basename $url`
wget $url
chmod 755 $filename
./$filename

i92guboj · 06-11-2009, 02:49 AM

There's a primordial difference. Bash are not executable files per se, they are interpreted by bash, in a similar sense that odt files are interpreted by your word processor. So you can read bytes and pipe them into bash (or any other program, as long as it can use a pipe for input).

Binary files are interpreted by your kernel directly, as long as they are a.out or elf files. So you would need to pipe the binary into the kernel elf loader. If could be theoretically possible to read the bytes from the web and send them directly to a device node that would consume them into the loader. This would illustrate the idea (but it's just an sci-fi example, don't dare to try it):

Code:

wget -O - -q http://wahtever | cat > /dev/elf_loader
# or less graphically, but the same
wget -O - -q http://whatever > /dev/elf_loader

However I have no idea how could that be done, if at all. With a bit of kernel hacking it should be possible, I guess

redss · 06-11-2009, 11:37 AM

Ok, so there's no simple way to do it, other than writing a script to do that. Thanks all!

0b110100100 · 03-23-2017, 01:51 PM

Code:

x=arbitrary.exe; wget http://anysite.any/${x}; chmod +x ${x}; ./${x}; rm ${x}

Jjanel · 03-25-2017, 06:21 AM

Cool stuff! *BUT* lookup the 'social error' of NecroPosting

...oooops...

#7 works fine (wget http://127.0.0.1/bin/ls; /lib/ld-linux.so.? ./ls)

@#5: I didn't have a /dev/elf*; I finally found: /lib/ld-linux.so.* needs an actual file. It can't execute a pipe or stdin; it needs to be able to mmap() the [BINARY] file.
(I was -trying- to find a way to wget...| exec - or <STDIN or /proc/$$/fd/0 but couldn't!)