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telegram-bot-bash
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doc: better explanation of $ RCE

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Kay Marquardt (Gnadelwartz) 2020-12-29 13:03:46 +01:00
parent d083390dcb
commit a5307e3a94
4 changed files with 63 additions and 52 deletions
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20
README.html
View File

@ -327,7 +327,7 @@ This is bashbot, the Telegram bot written entirely in bash.
It features background tasks and interactive chats, and can serve as an interface for CLI programs.</code></pre>
<p>For more Information on how to install, customize and use your new bot, read the <a href="#Documentation">Documentation</a></p>
<h3>Log files</h3>
<p>Bashbot actions are logged in BASHBOT.log, Telegram send/receive errors are logged to ERROR.log. Start bashbot in debug mode to get all messages send to / received from Telegram and error messages of bash commands also.</p>
<p>Bashbot actions are logged to <code>BASHBOT.log</code>, Telegram send/receive errors are logged to <code>ERROR.log</code>. Start bashbot in debug mode to get all messages send to / received from Telegram and error messages of bash commands also.</p>
<p>To enable debug mode start bashbot with debug as third argument: <code>bashbot start debug</code></p>
<pre><code>├── logs
│   ├── BASHBOT.log # log what your bot is doing ...
@ -339,8 +339,8 @@ It features background tasks and interactive chats, and can serve as an interfac
<h2>Security Considerations</h2>
<p>Running a Telegram Bot means it is connected to the public and you never know what's send to your Bot.</p>
<p>Bash scripts in general are not designed to be bullet proof, so consider this Bot as a proof of concept. Bash programmers often struggle with 'quoting hell' and globbing, see <a href="https://unix.stackexchange.com/questions/171346/security-implications-of-forgetting-to-quote-a-variable-in-bash-posix-shells">Implications of wrong quoting</a></p>
<p>Whenever you are processing input from untrusted sources (messages, files, network) you must be as careful as possible, e.g. set IFS appropriate, disable globbing (set -f) and quote everything. In addition delete unused scripts and examples from your Bot, e.g. scripts 'notify', 'calc', 'question', and disable all not used commands.</p>
<p>One of the most powerful features of unix shells is variable and command substitution using <code>${}</code> and <code>$()</code>, but as they are expanded in double quotes, this can lead to RCE and information disclosing bugs in complex scripts like bashbot. So it's more secure to escape or remove '$' in input from user, files or network.</p>
<p>Whenever you are processing input from untrusted sources (messages, files, network) you must be as careful as possible, e.g. set IFS appropriate, disable globbing (set -f) and quote everything. In addition remove unused scripts and examples from your Bot, e.g. everything in <code>example/</code> and disable/remove all not needed bot commands.</p>
<p>It's important to escape or remove <code>$</code> in input from user, files or network (<em>as bashbot does</em>) One of the powerful features of unix shells are variable and command substitution using <code>${}</code> and<code>$()</code>, this can lead to remove code execution (RCE) or information disclosing bugs if unescaped <code>$</code> is included in untrusted input, e.g. <code>$$</code> or <code>$(rm -rf /*)</code></p>
<p>A powerful tool to improve your scripts is <code>shellcheck</code>. You can <a href="https://www.shellcheck.net/">use it online</a> or <a href="https://github.com/koalaman/shellcheck#installing">install shellcheck locally</a>. Shellcheck is used extensively in bashbot development to ensure a high code quality, e.g. it's not allowed to push changes without passing all shellcheck tests. In addition bashbot has a <a href="doc/7_develop.md">test suite</a> to check if important functionality is working as expected.</p>
<h3>Use printf whenever possible</h3>
<p>If you're writing a script and it is taking external input (from the user as arguments or file system...), you shouldn't use echo to display it. <a href="https://unix.stackexchange.com/a/6581">Use printf whenever possible</a></p>
@ -349,8 +349,8 @@ It features background tasks and interactive chats, and can serve as an interfac
<p><strong>Never run your Bot as root, this is the most dangerous you can do!</strong> Usually the user 'nobody' has almost no rights on unix/linux systems. See <a href="doc/4_expert.md">Expert use</a> on how to run your Bot as an other user.</p>
<h3>Secure your Bot installation</h3>
<p><strong>Your Bot configuration must no be readable from other users.</strong> Everyone who can read your Bots token is able to act as your Bot and has access to all chats the Bot is in!</p>
<p>Everyone with read access to your Bot files can extract your Bots data. Especially your Bot config in <code>config.jssh</code> must be protected against other users. No one except you should have write access to the Bot files. The Bot should be restricted to have write access to <code>count.jssh</code> and <code>data-bot-bash</code> only, all other files must be write protected.</p>
<p>To set access rights for your bashbot installation to a reasonable default run <code>sudo ./bashbot.sh init</code> after every update or change to your installation directory.</p>
<p>Everyone with read access to your Bot files can extract your Bots data. Especially your Bot config in<code>config.jssh</code> must be protected against other users. No one except you should have write access to the Bot files. The Bot should be restricted to have write access to<code>count.jssh</code> and <code>data-bot-bash</code> only, all other files must be write protected.</p>
<p>To set access rights for your bashbot installation to a reasonable default run<code>sudo ./bashbot.sh init</code> after every update or change to your installation directory.</p>
<h2>FAQ</h2>
<h3>Is this Bot insecure?</h3>
<p>Bashbot is not more (in)secure as any Bot written in an other language, we have done our best to make it as secure as possible. But YOU are responsible for the bot commands you wrote and you should know about the risks ...</p>
@ -364,11 +364,11 @@ It features background tasks and interactive chats, and can serve as an interfac
<li>no database, not event driven, not object oriented ...</li>
</ul>
<h3>Can I have the single bashbot.sh file back?</h3>
<p>At the beginning bashbot was simply the file <code>bashbot.sh</code> you can copy everywhere and run the bot. Now we have 'commands.sh', 'mycommands.sh', 'modules/*.sh' and much more.</p>
<p>Hey no Problem, if you are finished with your cool bot run <code>dev/make-standalone.sh</code> to create a stripped down Version of your bot containing only 'bashbot.sh' and 'commands.sh'! For more information see <a href="doc/7_develop.md">Create a stripped down Version of your Bot</a></p>
<p>At the beginning bashbot was simply the file<code>bashbot.sh</code> you can copy everywhere and run the bot. Now we have 'commands.sh', 'mycommands.sh', 'modules/*.sh' and much more.</p>
<p>Hey no Problem, if you are finished with your cool bot run<code>dev/make-standalone.sh</code> to create a stripped down Version of your bot containing only 'bashbot.sh' and 'commands.sh'! For more information see <a href="doc/7_develop.md">Create a stripped down Version of your Bot</a></p>
<h3>Can I send messages from CLI and scripts?</h3>
<p>Of course, you can send messages from CLI and scripts, simply install bashbot as <a href="#Your-really-first-bashbot-in-a-nutshell">described here</a>, send the message '/start' to set yourself as botadmin and stop the bot with <code>./bashbot.sh stop</code>.</p>
<p>Bashbot provides some ready to use scripts ro send messages from command line in <code>bin/</code> dir, e.g. <code>send_message.sh</code>.</p>
<p>Of course, you can send messages from command line and scripts, simply install bashbot as <a href="#Your-really-first-bashbot-in-a-nutshell">described here</a>, send the message '/start' to set yourself as botadmin and then stop the bot with <code>./bashbot.sh stop</code>.</p>
<p>Bashbot provides some ready to use scripts for sending messages from command line in <code>bin/</code> dir, e.g. <code>send_message.sh</code>.</p>
<div class="sourceCode" id="cb4"><pre class="sourceCode bash"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="ex">bin/send_message.sh</span> BOTADMIN <span class="st">&quot;This is my first message send from CLI&quot;</span></span>
<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a><span class="ex">bin/send_message.sh</span> <span class="at">--help</span></span></code></pre></div>
@ -390,6 +390,6 @@ It features background tasks and interactive chats, and can serve as an interfac
<p>@Gnadelwartz</p>
<h2>That's it all guys!</h2>
<p>If you feel that there's something missing or if you found a bug, feel free to submit a pull request!</p>
<h4>$$VERSION$$ v1.21-dev-28-g43f5536</h4>
<h4>$$VERSION$$ v1.21-dev-33-gd083390</h4>
</body>
</html>

20
README.md
View File

@ -137,15 +137,21 @@ To enable debug mode start bashbot with debug as third argument: `bashbot start
## Security Considerations
Running a Telegram Bot means it is connected to the public and you never know what's send to your Bot.
Bash scripts in general are not designed to be bullet proof, so consider this Bot as a proof of concept. Bash programmers often struggle with 'quoting hell' and globbing, see [Implications of wrong quoting](https://unix.stackexchange.com/questions/171346/security-implications-of-forgetting-to-quote-a-variable-in-bash-posix-shells)
Bash scripts in general are not designed to be bullet proof, so consider this Bot as a proof of concept.
Bash programmers often struggle with 'quoting hell' and globbing,
see [Implications of wrong quoting](https://unix.stackexchange.com/questions/171346/security-implications-of-forgetting-to-quote-a-variable-in-bash-posix-shells)
Whenever you are processing input from untrusted sources (messages, files, network) you must be as careful as possible, e.g. set IFS appropriate, disable globbing (set -f) and quote everything. In addition delete unused scripts and examples from your Bot, e.g. scripts 'notify', 'calc', 'question', and disable all not used commands.
Whenever you are processing input from untrusted sources (messages, files, network) you must be as careful as possible,
e.g. set IFS appropriate, disable globbing (set -f) and quote everything. In addition remove unused scripts and examples
from your Bot, e.g. everything in `example/` and disable/remove all not needed bot commands.
One of the most powerful features of unix shells is variable and command substitution using`${}` and`$()```,
but as they are expanded in double quotes, this can lead to RCE and information disclosing bugs in complex scripts like bashbot.
So it's more secure to escape or remove '$' in input from user, files or network.
It's important to escape or remove `$` in input from user, files or network (_as bashbot does_)
One of the powerful features of unix shells are variable and command substitution using `${}` and`$()`,
this can lead to remove code execution (RCE) or information disclosing bugs if unescaped `$` is included in untrusted input, e.g. `$$` or `$(rm -rf /*)`
A powerful tool to improve your scripts is`shellcheck`. You can [use it online](https://www.shellcheck.net/) or [install shellcheck locally](https://github.com/koalaman/shellcheck#installing). Shellcheck is used extensively in bashbot development to ensure a high code quality, e.g. it's not allowed to push changes without passing all shellcheck tests.
A powerful tool to improve your scripts is `shellcheck`. You can [use it online](https://www.shellcheck.net/) or
[install shellcheck locally](https://github.com/koalaman/shellcheck#installing). Shellcheck is used extensively in bashbot development
to ensure a high code quality, e.g. it's not allowed to push changes without passing all shellcheck tests.
In addition bashbot has a [test suite](doc/7_develop.md) to check if important functionality is working as expected.
### Use printf whenever possible
@ -233,4 +239,4 @@ See `mycommnds.sh.dist` for an example.
If you feel that there's something missing or if you found a bug, feel free to submit a pull request!
#### $$VERSION$$ v1.21-dev-29-g13d15f4
#### $$VERSION$$ v1.21-dev-33-gd083390

70
README.txt
View File

@ -143,8 +143,8 @@ the [Documentation](#Documentation)
### Log files
Bashbot actions are logged in BASHBOT.log, Telegram send/receive errors are
logged to ERROR.log.
Bashbot actions are logged to `BASHBOT.log`, Telegram send/receive errors are
logged to `ERROR.log`.
Start bashbot in debug mode to get all messages send to / received from
Telegram and error messages of bash commands also.
@ -168,29 +168,33 @@ Running a Telegram Bot means it is connected to the public and you never know
what's send to your Bot.
Bash scripts in general are not designed to be bullet proof, so consider this
Bot as a proof of concept. Bash programmers often struggle with 'quoting hell'
and globbing, see [Implications of wrong
Bot as a proof of concept.
Bash programmers often struggle with 'quoting hell' and globbing,
see [Implications of wrong
quoting](https://unix.stackexchange.com/questions/171346/security-implications-o
f-forgetting-to-quote-a-variable-in-bash-posix-shells)
Whenever you are processing input from untrusted sources (messages, files,
network) you must be as careful as possible, e.g. set IFS appropriate, disable
globbing (set -f) and quote everything. In addition delete unused scripts and
examples from your Bot, e.g. scripts 'notify', 'calc', 'question', and disable
all not used commands.
network) you must be as careful as possible,
e.g. set IFS appropriate, disable globbing (set -f) and quote everything. In
addition remove unused scripts and examples
from your Bot, e.g. everything in `example/` and disable/remove all not needed
bot commands.
One of the most powerful features of unix shells is variable and command
substitution using ```${}``` and ```$()```,
but as they are expanded in double quotes, this can lead to RCE and information
disclosing bugs in complex scripts like bashbot.
So it's more secure to escape or remove '$' in input from user, files or
network.
It's important to escape or remove `$` in input from user, files or network
(_as bashbot does_)
One of the powerful features of unix shells are variable and command
substitution using `${}` and`$()`,
this can lead to remove code execution (RCE) or information disclosing bugs if
unescaped `$` is included in untrusted input, e.g. `$$` or `$(rm -rf /*)`
A powerful tool to improve your scripts is ```shellcheck```. You can [use it
online](https://www.shellcheck.net/) or [install shellcheck
A powerful tool to improve your scripts is `shellcheck`. You can [use it
online](https://www.shellcheck.net/) or
[install shellcheck
locally](https://github.com/koalaman/shellcheck#installing). Shellcheck is used
extensively in bashbot development to ensure a high code quality, e.g. it's not
allowed to push changes without passing all shellcheck tests.
extensively in bashbot development
to ensure a high code quality, e.g. it's not allowed to push changes without
passing all shellcheck tests.
In addition bashbot has a [test suite](doc/7_develop.md) to check if important
functionality is working as expected.
@ -218,13 +222,13 @@ can read your Bots token is able to act as your Bot and has access to all chats
the Bot is in!
Everyone with read access to your Bot files can extract your Bots data.
Especially your Bot config in ```config.jssh``` must be protected against other
Especially your Bot config in`config.jssh` must be protected against other
users. No one except you should have write access to the Bot files. The Bot
should be restricted to have write access to ```count.jssh``` and
```data-bot-bash``` only, all other files must be write protected.
should be restricted to have write access to`count.jssh` and `data-bot-bash`
only, all other files must be write protected.
To set access rights for your bashbot installation to a reasonable default run
```sudo ./bashbot.sh init``` after every update or change to your installation
To set access rights for your bashbot installation to a reasonable default
run`sudo ./bashbot.sh init` after every update or change to your installation
directory.
## FAQ
@ -249,24 +253,24 @@ health status
- no database, not event driven, not object oriented ...
### Can I have the single bashbot.sh file back?
At the beginning bashbot was simply the file ```bashbot.sh``` you can copy
At the beginning bashbot was simply the file`bashbot.sh` you can copy
everywhere and run the bot. Now we have 'commands.sh', 'mycommands.sh',
'modules/*.sh' and much more.
Hey no Problem, if you are finished with your cool bot run
```dev/make-standalone.sh``` to create a stripped down Version of your bot
Hey no Problem, if you are finished with your cool bot
run`dev/make-standalone.sh` to create a stripped down Version of your bot
containing only
'bashbot.sh' and 'commands.sh'! For more information see [Create a stripped
down Version of your Bot](doc/7_develop.md)
### Can I send messages from CLI and scripts?
Of course, you can send messages from CLI and scripts, simply install bashbot
as [described here](#Your-really-first-bashbot-in-a-nutshell),
send the message '/start' to set yourself as botadmin and stop the bot with
```./bashbot.sh stop```.
Of course, you can send messages from command line and scripts, simply install
bashbot as [described here](#Your-really-first-bashbot-in-a-nutshell),
send the message '/start' to set yourself as botadmin and then stop the bot
with `./bashbot.sh stop`.
Bashbot provides some ready to use scripts ro send messages from command line
in `bin/` dir, e.g. `send_message.sh`.
Bashbot provides some ready to use scripts for sending messages from command
line in `bin/` dir, e.g. `send_message.sh`.
```bash
bin/send_message.sh BOTADMIN "This is my first message send from CLI"
@ -315,4 +319,4 @@ See `mycommnds.sh.dist` for an example.
If you feel that there's something missing or if you found a bug, feel free to
submit a pull request!
#### $$VERSION$$ v1.21-dev-28-g43f5536
#### $$VERSION$$ v1.21-dev-33-gd083390

5
modules/jsonDB.sh
View File

@ -5,7 +5,7 @@
# This file is public domain in the USA and all free countries.
# Elsewhere, consider it to be WTFPLv2. (wtfpl.net/txt/copying)
#
#### $$VERSION$$ v1.20-0-g2ab00a2
#### $$VERSION$$ v1.21-dev-33-gd083390
#
# source from commands.sh to use jsonDB functions
#
@ -331,8 +331,9 @@ function jssh_updateArray_async() {
# read JSON.sh style data and asssign to an ARRAY
# $1 ARRAY name, must be declared with "declare -A ARRAY" before calling
Json2Array() {
# match ["....."]\t and replace \t with = and print quote true false escape not escaped $
# shellcheck disable=SC1091,SC1090
[ -z "$1" ] || source <( printf "$1"'=( %s )' "$(sed -E -n -e '/\["[-0-9a-zA-Z_,."]+"\]\+*\t/ s/\t/=/gp' -e 's/=(true|false)/="\1"/')" )
[ -z "$1" ] || source <( printf "$1"'=( %s )' "$(sed -E -n -e '/\["[-0-9a-zA-Z_,."]+"\]\+*\t/ s/\t/=/p' -e 's/=(true|false)/="\1"/' -e 's/([^\]|^)\$/\1\\$/g')" )
}
# get Config Key from jssh file without jsshDB
# output ARRAY as JSON.sh style data