Writing own script which will overcome another script .sh

vidar567 · 05-16-2022, 01:55 PM

In my system using cron.d there is a file which is repeatdly run. It generates an answer to my exercise.
I used ls /etc/cron.d I have access to this file.
It is alice.sh I use

Code:

 
sh /tmp/tmp.6vOX6HxEg1/alice.sh

my resposne

Code:

alice@ip-10-0-119-57:~$ sh /tmp/tmp.6vOX6HxEg1/alice.sh
cat: /root/archive/secret.txt: Permission denied
/opt/create_and_delete_file_from_args.sh: line 7: /tmp/tmp.6vOX6HxEg1/151504505d2d29ecad318671b5476560: Permission denied
rm: cannot remove '/tmp/tmp.6vOX6HxEg1/151504505d2d29ecad318671b5476560': No such file or directory

It generates a file that I need to read but it is as I read deleted.
I was thinking to run my own script which will listen and copy all kind of files when created to another directory. But I am green I do not know how to write own listener in bash linux.
Thanks in advance.

this is alice.sh

Code:

#!/usr/bin/env bash
  
secret_script_path="/opt/create_and_delete_file_from_args.sh"
secret_directory="/tmp/tmp.6vOX6HxEg1"
secret_file="TUApZ7WH3C7n"

bash "${secret_script_path}" "${secret_directory}" $(echo "${secret_file}" | md5sum | awk '{ print $1 }')

first edit:
this next .sh file has got a method that create and after 0,005s delete file with information.

EDIT:
This is my /opt/create_and_delete_file_from_args.sh file

Code:

#!/usr/bin/env bash

"secret_directory=$1
secret_file=$2
exercise_flag=$(cat "/root/archive/secret.txt")

echo "${exercise_flag}" > "${secret_directory}/${secret_file}"

sleep 0.005"

rm "${secret_directory}/${secret_file}"

I can't edit this file it is only readable I wanted to delete rm and add cat after creating.
There was an idea to create another .sh file without rm and with cat, but I can't do it.
After leaving vim I used

Code:

:w !sudo tee % > /dev/null

but there is error with

Code:

Username is not in the sudoers file. This incident will be reported

if I'm leaving with :w then "E212 Can't open file for writing"

slac-in-the-box · 05-16-2022, 02:30 PM

Quote:

Originally Posted by vidar567

Code:

/opt/create_and_delete_file_from_args.sh

Code:

cat: /root/archive/secret.txt: Permission denied

Consider the two snippets from you code above: the first is an additonal shell script that gets excuted, but even though you did not post the content from that script in the /opt/ folder, it clearly is trying to catalogue a file in the /root folder.

But you user seems to be named alice, not root, so why should your linux system let alice look at root's files? The /root folder is the home folder of the root user, and you need to be the root user to access it.

Therefore, you should try your script (assuming you trust it) with root privledges by using "sudo" first, or use "su -" and become root. Once you are rooted, you have permission to see contents of /root. Always be careful as root and only run scripts that you trust. What if /opt/create_and_delete_file_from_args.sh had a command like "rm -rf /" -- if you executed that as root user, you would delete everything on your system, until you deleted the ability to delete.

Be careful with your root user, keep it secret and safe.

teckk · 05-16-2022, 02:56 PM

Code:

secret_script_path="/opt/create_and_delete_file_from_args.sh"
secret_directory="/tmp/tmp.6vOX6HxEg1"
secret_file="TUApZ7WH3C7n"

echo "${secret_script_path}" "${secret_directory}" $(echo "${secret_file}" | md5sum | awk '{ print $1 }')
/opt/create_and_delete_file_from_args.sh /tmp/tmp.6vOX6HxEg1 151504505d2d29ecad318671b5476560

So I assume that create_and_delete_file_from_args.sh takes 2 args.

If you want help then post create_and_delete_file_from_args.sh

There is no way anyone could tell what you have, what is wrong, from what you have posted.

Who owns /tmp and the contents?

Code:

__ls -l /tmp
__ls -l /tmp/tmp.6vOX6HxEg1/alice.sh

Quote:

cat: /root/archive/secret.txt: Permission denied

You can't write to that unless you are root. You probably should not be writing anything there.

Etc.

Edit:
Sorry, cloudflare made me change ls to __ls, change it back.

vidar567 · 05-17-2022, 01:03 AM

This is my /opt/create_and_delete_file_from_args.sh file
Code:

Code:

#!/usr/bin/env bash

"secret_directory=$1
secret_file=$2
exercise_flag=$(cat "/root/archive/secret.txt")

echo "${exercise_flag}" > "${secret_directory}/${secret_file}"

sleep 0.005"

rm "${secret_directory}/${secret_file}"

I trust in 100% the code and exercises. This is university exercises, but I can't deal with this last step.

I basically need to change/write new script to have access, download the file which is created before it is deleted. Do you think you could help me with this?

descendant_command · 05-17-2022, 01:53 AM

Just comment out the last line of /opt/create_and_delete_file_from_args.sh and then read it at your leisure.

vidar567 · 05-17-2022, 02:17 AM

I can't edit it.

descendant_command · 05-17-2022, 02:38 AM

Why not?

vidar567 · 05-17-2022, 03:54 AM

I have errors to save such file, because i.e this is read only. I can't change permission of this file and after creating new one without it and just cat it immediately it show

Code:

Username is not in the sudoers file. This incident will be reported

yancek · 05-17-2022, 10:50 AM

The message in post 8 tells you exactly what the problem is. You are trying to edit a file that needs root permissions. If you can't log in as root, you can't do it. You can put an entry in the /etc/sudoers file to allow a user to execute a specific command but again, you need root permissions to do that.