SimJacker Attack: Overview and prevention coding in Python
The Overview
SimJacker is a type of cyber attack that targets SIM cards, which are used in mobile phones and other devices to authenticate and connect to mobile networks. These attacks exploit vulnerabilities in the SIM cards themselves, as well as in the mobile network infrastructure that they rely on. As a result, they can be used to steal sensitive information, intercept calls and text messages, and even track the location of a device.
One of the most concerning aspects of SimJacker attacks is that they can be used to target specific individuals. The attacker can use the device’s SIM card information to identify the target and then craft a tailored attack to exploit the specific vulnerabilities of that device. This makes it difficult for individuals to protect themselves, as they may not even be aware that they are being targeted.
The first known SimJacker attack was discovered by the cyber security firm AdaptiveMobile in 2019, the company found that a particular type of SMS message was being used to target specific individuals and organizations. The attackers were able to gain access to the SIM card’s memory, read and write to it, and even track the location of the device.
The vulnerability that Simjacker attacks exploit is a feature called the SIMalliance Toolkit, which is designed to allow mobile operators to perform remote SIM management and provisioning. However, a vulnerability in the toolkit can be exploited by attackers to gain access to the SIM card’s memory and execute arbitrary code.
Basic Prevention and Protection Techniques
By Individuals and Organisations:
To protect against SimJacker attacks, individuals and organizations should take the following steps:
- Keep your mobile device and SIM card updated with the latest security patches.
- Be cautious of unexpected or suspicious SMS messages, especially those that contain links or attachments.
- Avoid clicking on links or downloading attachments from unknown or untrusted sources.
- Use a mobile security app that can detect and block SimJacker attacks.
- Contact your mobile operator if you suspect that your SIM card has been compromised.
By Mobile operators and SIM card manufacturers:
In addition to these steps, mobile operators and SIM card manufacturers should also take steps to address the vulnerabilities that are being exploited by SimJacker attacks. This includes:
- Regularly reviewing and patching the SIMalliance Toolkit to address known vulnerabilities.
- Developing new security features to better protect SIM cards and mobile devices from cyber attacks.
- Providing regular security updates to SIM cards to address newly discovered vulnerabilities.
- Improving security practices and training for employees who handle SIM card and mobile network management.
The SimJacker attacks highlight the need for better security for SIM cards and mobile devices. While individuals and organizations can take steps to protect themselves, it is ultimately up to mobile operators and SIM card manufacturers to address the underlying vulnerabilities that are being exploited by these attacks.
Specific coding examples that developers can use to protect against SimJacker attacks
One example is the use of a Secure Element (SE) in the SIM card. A SE is a secure, tamper-proof element that can store sensitive data and cryptographic keys. This can help protect against SimJacker attacks by making it more difficult for attackers to gain access to the SIM card’s memory and execute arbitrary code.
Another example is the use of Encryption to protect data transmitted between the SIM card and the mobile device. By encrypting the data, attackers will not be able to intercept and read the information, even if they are able to gain access to the SIM card’s memory.
Here is a sample code to encrypt data transmitted between the SIM card and the mobile device using Advanced Encryption Standard (AES) algorithm:
import base64
import hashlib
from Crypto.Cipher import AES
class AESCipher(object):
def __init__(self, key):
self.bs = AES.block_size
self.key = hashlib.sha256(key.encode()).digest()
def encrypt(self, raw):
raw = self._pad(raw)
cipher = AES.new(self.key, AES.MODE_ECB)
return base64.b64encode(cipher.encrypt(raw))
def decrypt(self, enc):
enc = base64.b64decode(enc)
cipher = AES.new(self.key, AES.MODE_ECB)
return self._unpad(cipher.decrypt(enc))
def _pad(self, s):
return s + (self.bs - len(s) % self.bs) * chr(self.bs - len(s) % self.bs)
def _unpad(self, s):
return s[:-ord(s[len(s)-1:])]
key = 'mysecretkey'
cipher = AESCipher(key)
# Encrypting data
enc_data = cipher.encrypt('my sensitive data')
print('Encrypted Data:', enc_data)
# Decrypting data
dec_data = cipher.decrypt(enc_data)
print('Decrypted Data:', dec_data)Another important aspect of protecting against SimJacker attacks is monitoring the SIM card’s activity and detecting any unusual or suspicious behavior. This can be done by analyzing log data from the SIM card and mobile device, as well as monitoring network traffic for signs of a SimJacker attack.
Here is a sample code to monitor the SIM card’s activity and detect any unusual or suspicious behavior using Python:
import os
import re
# Read SIM card log data
with open('sim_card.log', 'r') as f:
log_data = f.read()
# Search for suspicious activity
pattern = 'SIM card memory accessed|Location tracked|Unusual SMS received'
match = re.search(pattern, log_data)
if match:
print('Suspicious activity detected!')
print('Activity:', match.group(0))
else:
print('No suspicious activity detected.')It’s important to note that these coding examples are for illustration purpose only, and should be adapted and tested to work in specific environments and use cases. Additionally, it’s important to keep in mind that security is an ongoing process and not a one-time solution. As new vulnerabilities and attack methods are discovered, it’s important to regularly review and update security measures to ensure that they continue to be effective.
SimJacker attacks are a serious threat to mobile devices and networks, but by taking the necessary steps to protect against them, individuals, organizations, and mobile operators can help to mitigate the risks and keep their devices and networks secure.
Another important aspect of protecting against SimJacker attacks is ensuring that the SIM card and mobile device are configured securely. This includes disabling unnecessary services and features, using strong passwords and authentication methods, and implementing access controls to restrict who can access the SIM card and mobile device.
Here is a sample code to check the SIM card’s configuration using Python:
import subprocess
# Check SIM card services
services = subprocess.check_output(['adb', 'shell', 'service list'])
if 'sim-toolkit' in services:
print('SIM Toolkit service is enabled.')
else:
print('SIM Toolkit service is disabled.')
# Check SIM card password
password = subprocess.check_output(['adb', 'shell', 'gsm list'])
if 'Password: [enabled]' in password:
print('SIM card password is enabled.')
else:
print('SIM card password is disabled.')
Other research-based methods that can be used to protect against SimJacker attacks
One such method is using a technique called “Fuzzing” to test the SIM card for vulnerabilities. Fuzzing involves feeding the SIM card with a large number of random inputs and monitoring its behavior to see if it crashes or behaves in an unexpected way. This can help to identify vulnerabilities that could be exploited by attackers.
Here is a sample code to test the SIM card using Fuzzing technique:
import random
import time
# Generate random inputs
inputs = [''.join(random.choice(['A','B','C','D','E','F','0','1','2','3','4','5','6','7','8','9']) for i in range(16)) for j in range(10000)]
for input in inputs:
# Send input to SIM card
subprocess.call(['adb', 'shell', 'sim-toolkit', input])
time.sleep(0.01)
# Monitor SIM card's behavior
output = subprocess.check_output(['adb', 'shell', 'dmesg'])
if 'SIM card crash' in output:
print('Vulnerability found:', input)
breakAnother method is using a technique called “Dynamic Analysis” to analyze the SIM card’s behavior while it is running. This can help to identify any malicious activities and suspicious behavior that could indicate an attack.
Here is a sample code to analyze the SIM card’s behavior using the Dynamic Analysis technique:
import psutil
# Start monitoring SIM card's activity
subprocess.call(['adb', 'shell', 'start-monitor'])
# Monitor SIM card's process
while True:
sim_process = psutil.process_iter(['name', 'cmdline'])
for process in sim_process:
if 'sim-toolkit' in process.info['cmdline']:
if process.info['name'] == 'malicious_binary':
print('Malicious activity detected!')
subprocess.call(['adb', 'shell', 'kill', str(process.pid)])
break
time.sleep(1)It’s important to remember that these methods are for research purposes, and should be used with caution as they may cause unexpected behavior or crashes to the SIM card. Moreover, it’s necessary to test these methods in a safe environment and with the permission of the SIM card’s owner.
It’s also important to use them in a safe environment and on a non-production device.
Conclusion
Finally, it’s worth mentioning that there is no one-size-fits-all solution to protect against SimJacker attacks. It’s important to adopt a multi-layered approach that includes both technical and non-technical measures such as employee training, incident response plans, and regular security assessments.
In addition to these steps, it is also important to have a response plan in place in case a SimJacker attack is detected. This includes identifying the affected devices, isolating them from the network, and taking steps to contain the attack and prevent it from spreading. It’s also important to notify the appropriate authorities and work with them to investigate the attack and track down the attackers.
Simjacker attacks have shown that the threat to SIM cards is real, and it is important for mobile operators, manufacturers and users to be aware of the vulnerabilities and take the necessary steps to protect their devices and networks. As the threat landscape continues to evolve and attackers become more sophisticated, it is essential that all stakeholders work together to strengthen the security of SIM cards and mobile networks.
