CVE-2019-16256
📋 TL;DR
CVE-2019-16256 (Simjacker) is a vulnerability in the SIMalliance Toolbox Browser (S@T Browser) on UICC chips in mobile devices that allows remote attackers to send malicious SIM Toolkit instructions via SMS messages. This enables attackers to retrieve sensitive information like location data and IMEI numbers, execute commands, or access other device data without user interaction. The vulnerability primarily affects Samsung and other mobile devices with vulnerable SIM cards.
💻 Affected Systems
- Samsung mobile devices
- Other mobile devices with vulnerable SIM cards
📦 What is this software?
S\@t Browser by Trustedconnectivityalliance
⚠️ Risk & Real-World Impact
Worst Case
Attackers could track victims' real-time locations, steal personal data, execute arbitrary commands on the device, and potentially use the compromised device as an entry point for further attacks.
Likely Case
Targeted surveillance and data theft from specific individuals, with attackers harvesting location data, IMEI information, and potentially other device identifiers.
If Mitigated
Limited impact with proper SMS filtering, network-level protections, and updated SIM cards, though some information leakage might still occur.
🎯 Exploit Status
Exploitation requires sending specially crafted SMS messages to target devices. Attack has been observed in real-world surveillance campaigns.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: SIM card firmware updates from mobile operators
Vendor Advisory: https://www.adaptivemobile.com/blog/simjacker-next-generation-spying-over-mobile
Restart Required: No
Instructions:
1. Contact your mobile operator to check if your SIM card is vulnerable. 2. Request a SIM card replacement if vulnerable. 3. Mobile operators should deploy network-level filtering for malicious STK commands.
🔧 Temporary Workarounds
Disable STK/S@T Browser functionality
allDisable SIM Toolkit functionality on the device if possible
SMS filtering at network level
allMobile operators should implement filtering for malicious STK commands in SMS messages
🧯 If You Can't Patch
- Use devices from different mobile operators with updated SIM cards
- Consider using devices without SIM Toolkit functionality when possible
🔍 How to Verify
Check if Vulnerable:
Contact mobile operator to check SIM card vulnerability status. Check device for unexpected location sharing or unusual SMS activity.Check Version:
No direct command - requires contacting mobile operator for SIM card detailsVerify Fix Applied:
Confirm with mobile operator that SIM card has been replaced with non-vulnerable version. Monitor for suspicious SMS messages.📡 Detection & Monitoring
Log Indicators:
- Unusual SMS messages with binary/hex content
- Unexpected location sharing events
- SIM Toolkit command execution logs
Network Indicators:
- SMS messages containing STK commands to multiple devices
- Unusual SMS traffic patterns
SIEM Query:
sms_content CONTAINS "D0" OR sms_content CONTAINS "STK" AND sms_length > 160