CVE-2022-22805: Schneider Electric SMT UPS RCE Vulnerability

CVE-2022-22805 Overview

CVE-2022-22805 is a classic buffer overflow vulnerability (CWE-120) affecting Schneider Electric SmartConnect UPS devices. The vulnerability exists in the TLS packet reassembly process, where improper handling of input size during buffer copy operations allows remote attackers to execute arbitrary code on affected devices. This firmware vulnerability poses significant risks to critical infrastructure environments that rely on these uninterruptible power supply systems for operational continuity.

Critical Impact

Remote code execution on UPS devices through malformed TLS packets could allow attackers to disrupt power management systems, potentially causing physical damage to connected equipment or enabling further network compromise in critical infrastructure environments.

Affected Products

• Schneider Electric SMT Series (ID=1015) UPS firmware version 04.5 and prior
• Schneider Electric SMC Series (ID=1018) UPS firmware version 04.2 and prior
• Schneider Electric SMTL Series (ID=1026) UPS firmware version 02.9 and prior
• Schneider Electric SCL Series (ID=1029, 1030, 1036) UPS firmware version 02.5 and prior
• Schneider Electric SCL Series (ID=1037) UPS firmware version 03.1 and prior
• Schneider Electric SMX Series (ID=1031) UPS firmware version 03.1 and prior

Discovery Timeline

• March 9, 2022 - CVE-2022-22805 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-22805

Vulnerability Analysis

This vulnerability resides in the TLS implementation of Schneider Electric SmartConnect UPS firmware. The affected devices fail to properly validate the size of incoming TLS packets before copying data into fixed-size buffers during the packet reassembly process. When fragmented TLS records are reassembled, the firmware does not enforce adequate boundary checks, allowing an attacker to supply oversized data that overflows the destination buffer.

The vulnerability is exploitable remotely over the network without requiring authentication or user interaction. This makes it particularly dangerous for UPS devices that may be accessible on corporate networks or, in misconfigured environments, directly exposed to the internet. Successful exploitation grants the attacker complete control over the UPS device's firmware execution context.

Root Cause

The root cause is a classic buffer overflow condition (CWE-120) in the TLS packet reassembly routine. The firmware performs a buffer copy operation without validating that the input data size does not exceed the allocated buffer capacity. When processing reassembled TLS packets, the code fails to compare the incoming data length against the destination buffer's maximum size, allowing memory corruption beyond the intended boundaries.

Attack Vector

The attack is conducted over the network by sending specially crafted TLS packets to the vulnerable UPS device. An attacker can exploit this vulnerability by establishing a TLS connection to the device's network management interface and transmitting malformed packets designed to trigger the buffer overflow during reassembly.

The attacker crafts TLS records that, when fragmented and reassembled by the device, exceed the expected buffer size. During the reassembly process, the oversized data overwrites adjacent memory regions, potentially including return addresses or function pointers. By carefully controlling the overflow content, the attacker can redirect execution flow to achieve arbitrary code execution on the embedded system.

Detection Methods for CVE-2022-22805

Indicators of Compromise

• Unusual network traffic patterns to UPS management interfaces, particularly malformed or abnormally large TLS handshake packets
• Unexpected crashes or reboots of SmartConnect UPS devices
• Anomalous behavior from UPS devices such as unauthorized configuration changes or communication with unknown external hosts
• Network logs showing repeated TLS connection attempts from suspicious sources targeting UPS device ports

Detection Strategies

• Deploy network intrusion detection systems (IDS) with rules to identify malformed TLS packets targeting Schneider Electric UPS devices
• Implement network segmentation monitoring to detect unauthorized access attempts to ICS/OT network segments containing UPS infrastructure
• Enable detailed logging on firewalls and network devices to capture traffic destined for UPS management interfaces
• Utilize endpoint detection solutions capable of monitoring firmware behavior on connected industrial systems

Monitoring Recommendations

• Continuously monitor network traffic to and from all SmartConnect UPS devices for anomalous TLS traffic patterns
• Establish baseline behavior for UPS device network communications and alert on deviations
• Implement asset inventory management to track all affected UPS devices and their current firmware versions
• Configure SIEM rules to correlate alerts involving UPS device communications with known threat indicators

How to Mitigate CVE-2022-22805

Immediate Actions Required

• Apply firmware updates from Schneider Electric immediately for all affected SmartConnect UPS devices
• Isolate vulnerable UPS devices on dedicated network segments with strict access controls until patching is complete
• Disable remote network management interfaces on UPS devices if not operationally required
• Implement firewall rules to restrict access to UPS management ports to authorized management stations only

Patch Information

Schneider Electric has released security updates to address this vulnerability. Affected organizations should consult the Schneider Electric Security Advisory SEVD-2022-067-02 for specific firmware version information and download links. Update all SmartConnect Family devices including SMT, SMC, SMTL, SCL, and SMX series to the latest available firmware versions that remediate this buffer overflow vulnerability.

Workarounds

• Place all affected UPS devices behind firewalls and restrict network access to trusted management systems only
• Disable TLS-based remote management features if possible and use alternative out-of-band management methods
• Implement network-level filtering to block potentially malicious TLS traffic from reaching UPS devices
• Monitor and log all access attempts to UPS management interfaces for forensic analysis

# Example firewall rule to restrict UPS management access
# Allow only trusted management subnet to access UPS devices
iptables -A INPUT -s 10.0.100.0/24 -d 10.0.200.0/24 -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -d 10.0.200.0/24 -p tcp --dport 443 -j DROP