CVE-2020-35929
📋 TL;DR
CVE-2020-35929 is a critical vulnerability in TinyCheck where hard-coded credentials in the installation script allow attackers to gain unauthorized access to the backend. This affects all TinyCheck installations using versions before the fix. Attackers can potentially access sensitive monitoring data and system information.
💻 Affected Systems
- Kaspersky TinyCheck
📦 What is this software?
Tinycheck by Kaspersky
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the TinyCheck backend, allowing attackers to access all monitored network traffic, modify configurations, and potentially pivot to other systems.
Likely Case
Unauthorized access to sensitive network monitoring data and system information collected by TinyCheck.
If Mitigated
Limited impact with proper network segmentation and access controls preventing external access to the backend interface.
🎯 Exploit Status
Exploitation is trivial - attackers simply need to access the backend interface using the hard-coded credentials.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after commits 9fd360d and ea53de8
Vendor Advisory: https://github.com/KasperskyLab/TinyCheck/security/advisories/GHSA-9f7g-72h2-59g7
Restart Required: Yes
Instructions:
1. Update TinyCheck to version after commits 9fd360d and ea53de8. 2. Reinstall TinyCheck completely to ensure hard-coded credentials are removed. 3. Change any passwords that may have been compromised. 4. Restart the TinyCheck service.
🔧 Temporary Workarounds
Change Backend Credentials
linuxManually change the backend credentials to prevent exploitation
# Edit TinyCheck configuration to change default credentials
# Location depends on installation, typically in config files
Network Isolation
linuxRestrict access to TinyCheck backend interface
sudo iptables -A INPUT -p tcp --dport [TINYCHECK_PORT] -s [TRUSTED_IPS] -j ACCEPT
sudo iptables -A INPUT -p tcp --dport [TINYCHECK_PORT] -j DROP
🧯 If You Can't Patch
- Immediately change all default credentials and implement strong authentication
- Isolate TinyCheck backend behind firewall, allowing access only from trusted networks
🔍 How to Verify
Check if Vulnerable:
Check if TinyCheck installation script contains hard-coded credentials by examining the installation files for default username/password combinations.Check Version:
Check git commit history or version files in the TinyCheck installation directoryVerify Fix Applied:
Verify that the installation script no longer contains hard-coded credentials and that backend authentication requires unique credentials.📡 Detection & Monitoring
Log Indicators:
- Failed authentication attempts followed by successful logins with default credentials
- Multiple login attempts from unusual IP addresses
Network Indicators:
- Unauthorized access to TinyCheck backend port
- Traffic patterns indicating data exfiltration from TinyCheck
SIEM Query:
source="tinycheck" AND (event_type="authentication" AND result="success" AND user="default_user")