CVE-2021-46416 – This vulnerability allows unauthorized user gro... (How to Fix)

Q: What is the severity of CVE-2021-46416?

CVE-2021-46416 has a CVSS score of 8.1 (HIGH). This vulnerability allows unauthorized user groups to access restricted functionality in SMA SUNNY TRIPOWER 5.0 inverters due to insecure cookie handling. Attackers can manipulate cookie values to bypass authorization checks and gain elevated privileges. This affects all systems running the vulnerable firmware version.

📋 TL;DR

This vulnerability allows unauthorized user groups to access restricted functionality in SMA SUNNY TRIPOWER 5.0 inverters due to insecure cookie handling. Attackers can manipulate cookie values to bypass authorization checks and gain elevated privileges. This affects all systems running the vulnerable firmware version.

💻 Affected Systems

Products:

SMA SUNNY TRIPOWER 5.0

Versions: Firmware version 3.10.16.R

Operating Systems: Embedded firmware

Default Config Vulnerable: ⚠️ Yes

Notes: All systems running the vulnerable firmware version are affected. The vulnerability exists in the web interface authentication mechanism.

📦 What is this software?

Sunny Tripower Firmware by Sma

View all CVEs affecting Sunny Tripower Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete compromise of inverter control systems allowing attackers to modify power generation settings, disrupt operations, or cause physical damage to equipment.

🟠

Likely Case

Unauthorized access to monitoring data, configuration settings, and limited control functions by attackers with network access.

🟢

If Mitigated

Limited information disclosure or minor configuration changes if proper network segmentation and access controls are implemented.

🌐 Internet-Facing: HIGH - Solar inverters are often connected to monitoring systems accessible via internet, making them directly exploitable from external networks.

🏢 Internal Only: MEDIUM - Attackers with internal network access could exploit this vulnerability to gain unauthorized control of inverter systems.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploitation requires network access to the inverter's web interface and basic knowledge of cookie manipulation. Public proof-of-concept demonstrates the vulnerability.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check SMA Security Advisory for latest patched version

Vendor Advisory: https://www.sma.de/en/products/solarinverters/sunny-tripower-30-40-50-60.html

Restart Required: Yes

Instructions:

1. Check current firmware version. 2. Download latest firmware from SMA portal. 3. Upload firmware to inverter via web interface. 4. Reboot inverter to apply update.

🔧 Temporary Workarounds

Network Segmentation

all

Isolate inverter management interfaces from untrusted networks

Access Control Lists

all

Restrict network access to inverter management interfaces to authorized IP addresses only

🧯 If You Can't Patch

Implement strict network segmentation to isolate inverters from untrusted networks
Deploy web application firewall rules to detect and block cookie manipulation attempts

🔍 How to Verify

Check if Vulnerable:

Check firmware version in inverter web interface under System Information. If version is 3.10.16.R, system is vulnerable.

Check Version:

Access inverter web interface and navigate to System > Information to view firmware version

Verify Fix Applied:

Verify firmware version has been updated to a version later than 3.10.16.R. Test authentication bypass attempts should fail.

📡 Detection & Monitoring

Log Indicators:

Multiple failed authentication attempts followed by successful access with unusual user IDs
Access to restricted URLs without proper authentication logs

Network Indicators:

HTTP requests with manipulated cookie values
Unusual access patterns to inverter management interface

SIEM Query:

source="inverter_web_logs" AND (cookie="userid=*" OR url="/admin/*") AND NOT auth_success="true"

📊 Metadata

CVE ID: CVE-2021-46416

CVSS v3 Score: 8.1 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

CWE: CWE-639

Published: April 7, 2022

Last Updated: November 21, 2024

🔗 References

http://packetstormsecurity.com/files/166670/SAM-SUNNY-TRIPOWER-5.0-Insecure-Direct-Object-Reference.html Exploit,Third Party Advisory,VDB Entry
https://drive.google.com/drive/folders/1BPULhDC_g__seH_VnQlVtkrKdOLkXdzV?usp=sharing Exploit,Third Party Advisory
https://www.sma.de/en/products/solarinverters/sunny-tripower-30-40-50-60.html Product,Vendor Advisory
http://packetstormsecurity.com/files/166670/SAM-SUNNY-TRIPOWER-5.0-Insecure-Direct-Object-Reference.html Exploit,Third Party Advisory,VDB Entry
https://drive.google.com/drive/folders/1BPULhDC_g__seH_VnQlVtkrKdOLkXdzV?usp=sharing Exploit,Third Party Advisory
https://www.sma.de/en/products/solarinverters/sunny-tripower-30-40-50-60.html Product,Vendor Advisory

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