CVE-2021-25502
📋 TL;DR
This vulnerability allows attackers to read the ESN (Electronic Serial Number) value without proper privileges on affected Samsung devices. The ESN is a sensitive identifier that could be used for device tracking or other malicious purposes. This affects Samsung devices running software versions prior to the November 2021 security update.
💻 Affected Systems
- Samsung mobile devices
📦 What is this software?
Android by Google
Android by Google
Android by Google
Android by Google
⚠️ Risk & Real-World Impact
Worst Case
Attackers could obtain the unique ESN identifier, potentially enabling device tracking, cloning, or other identity-based attacks against the device owner.
Likely Case
Local attackers or malicious apps could access the ESN value without proper authorization, compromising device privacy and potentially enabling targeted attacks.
If Mitigated
With proper access controls and the security patch applied, only authorized system components can access sensitive ESN information.
🎯 Exploit Status
Exploitation likely requires local access or malicious app installation. The CWE-269 (Improper Privilege Management) suggests privilege escalation is involved.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: SMR Nov-2021 Release 1 or later
Vendor Advisory: https://security.samsungmobile.com/securityUpdate.smsb?year=2021&month=11
Restart Required: Yes
Instructions:
1. Go to Settings > Software update on your Samsung device. 2. Tap Download and install. 3. Apply the November 2021 security update. 4. Restart the device when prompted.
🔧 Temporary Workarounds
Restrict app permissions
allReview and restrict unnecessary app permissions, especially those requesting device identification or system settings access.
Avoid untrusted apps
allOnly install apps from official app stores and avoid sideloading applications from untrusted sources.
🧯 If You Can't Patch
- Implement mobile device management (MDM) policies to restrict app installations and monitor for suspicious behavior.
- Use network segmentation to isolate vulnerable devices from critical systems and monitor for unusual network traffic.
🔍 How to Verify
Check if Vulnerable:
Check device software version in Settings > About phone > Software information. If the security patch level is earlier than November 2021, the device is vulnerable.Check Version:
Not applicable - check through device settings UIVerify Fix Applied:
Verify the security patch level shows 'November 1, 2021' or later in Settings > About phone > Software information.📡 Detection & Monitoring
Log Indicators:
- Unusual access attempts to device identification APIs or Property Settings
- Apps requesting ESN or IMEI permissions without clear need
Network Indicators:
- Unusual device identifier transmissions to external servers
- Suspicious network traffic from apps accessing device identification services
SIEM Query:
Not specifically provided - monitor for apps accessing android.permission.READ_PHONE_STATE or similar device identification permissions