CVE-2020-7845
📋 TL;DR
CVE-2020-7845 is a stack-based buffer overflow vulnerability in Spamsniper email security software versions 5.0 through 5.2.7. It allows remote attackers to execute arbitrary code by sending a specially crafted MAIL FROM command. Organizations using vulnerable Spamsniper versions for email filtering are affected.
💻 Affected Systems
- Spamsniper
📦 What is this software?
Spamsniper by Jiransecurity
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with SYSTEM/root privileges leading to complete system compromise, data exfiltration, and lateral movement within the network.
Likely Case
Service disruption, denial of service, or limited code execution depending on exploit sophistication and system hardening.
If Mitigated
Denial of service or crash of the Spamsniper service without code execution if exploit fails or protections like DEP/ASLR are effective.
🎯 Exploit Status
The vulnerability requires sending a malicious MAIL FROM command, which is part of standard SMTP protocol and doesn't require authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.2.8 or later
Vendor Advisory: https://www.jiransecurity.com/
Restart Required: Yes
Instructions:
1. Download Spamsniper version 5.2.8 or later from the vendor website. 2. Backup current configuration. 3. Run the installer to upgrade. 4. Restart the Spamsniper service. 5. Verify the new version is running.
🔧 Temporary Workarounds
Network Segmentation
allRestrict SMTP access to Spamsniper server to only trusted email sources
Input Validation Filter
allDeploy network filter or proxy to validate MAIL FROM command length before reaching Spamsniper
🧯 If You Can't Patch
- Isolate the Spamsniper server in a DMZ with strict firewall rules limiting SMTP access
- Implement network-based intrusion prevention system (IPS) with rules to detect buffer overflow attempts in SMTP commands
🔍 How to Verify
Check if Vulnerable:
Check Spamsniper version in the software interface or registry: HKEY_LOCAL_MACHINE\SOFTWARE\JiranSecurity\Spamsniper\VersionCheck Version:
reg query "HKLM\SOFTWARE\JiranSecurity\Spamsniper" /v VersionVerify Fix Applied:
Verify version is 5.2.8 or higher and test SMTP functionality with normal email traffic📡 Detection & Monitoring
Log Indicators:
- Unusually long MAIL FROM commands in SMTP logs
- Spamsniper service crashes or restarts
- Error messages related to buffer overflow
Network Indicators:
- SMTP packets with MAIL FROM commands exceeding typical length (e.g., > 1000 characters)
- Multiple connection attempts to Spamsniper SMTP port (typically 25)
SIEM Query:
source="spamsniper_logs" AND ("MAIL FROM" AND length>1000) OR "buffer overflow" OR "access violation"