CVE-2020-35926
📋 TL;DR
This vulnerability in the nanorand Rust crate causes random number generators to return all zero values due to integer truncation. This affects any Rust application using nanorand for cryptographic operations, authentication tokens, or security-sensitive random values. Attackers can predict or manipulate supposedly random values.
💻 Affected Systems
- Rust applications using nanorand crate
📦 What is this software?
Nanorand by Nanorand Project
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of cryptographic systems, predictable authentication tokens, broken encryption, and bypass of security controls relying on randomness.
Likely Case
Predictable session tokens, weak cryptographic keys, and compromised security mechanisms that depend on random number generation.
If Mitigated
Limited impact if application doesn't use nanorand for security-critical operations or has additional randomness sources.
🎯 Exploit Status
Exploitation requires the attacker to interact with the vulnerable application's random number generation functionality.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: nanorand 0.5.1 and later
Vendor Advisory: https://rustsec.org/advisories/RUSTSEC-2020-0089.html
Restart Required: Yes
Instructions:
1. Update Cargo.toml to require nanorand >=0.5.1
2. Run 'cargo update nanorand'
3. Rebuild and redeploy your application
4. Test random number generation functionality
🔧 Temporary Workarounds
Replace nanorand with alternative RNG
allTemporarily switch to a different random number generator crate like rand or fastrand
cargo remove nanorand
cargo add rand
🧯 If You Can't Patch
- Implement additional entropy sources alongside nanorand
- Audit all uses of random values for security impact and add validation
🔍 How to Verify
Check if Vulnerable:
Check Cargo.lock or Cargo.toml for nanorand version <0.5.1Check Version:
grep nanorand Cargo.lock | grep versionVerify Fix Applied:
Verify nanorand >=0.5.1 in Cargo.lock and test random number generation📡 Detection & Monitoring
Log Indicators:
- Repeated zero values from random functions
- Failed cryptographic operations
- Unexpected authentication patterns
Network Indicators:
- Predictable session tokens or nonces in network traffic
SIEM Query:
Application logs showing repeated identical values from random generation functions