SEC Consult Vulnerability Lab Security Advisory < 20210714-0 >  
title: Authentication bypass & Remote code execution  
product: Multiple Schneider Electric EVlink Charging Stations  
vulnerable version: Firmware R7 (Version V3.3.0.15)  
fixed version: Firmware R8 (Version V3.4.0.1)  
CVE number: CVE-2021-22707, CVE-2021-22708  
impact: Critical  
homepage: <>  
found: 2021-03-08  
by: Stefan Viehböck (Office Vienna)  
SEC Consult Vulnerability Lab  
An integrated part of SEC Consult, an Atos company  
Europe | Asia | North America <>  
Vendor description:  
"Our mission is to be your digital partner for Sustainability and Efficiency.  
We drive digital transformation by integrating world-leading process and energy  
technologies, end-point to cloud connecting products, controls, software and  
services, across the entire lifecycle, enabling integrated company management,  
for homes, buildings, data centers, infrastructure and industries.  
We are the most local of global companies. We are advocates of open standards  
and partnership ecosystems that are passionate about our shared Meaningful  
Purpose, Inclusive and Empowered values."  
Source: <>  
Business recommendation:  
The vendor provides a firmware update for the affected charging stations which  
should be installed immediately.  
SEC Consult highly recommends to perform a thorough security review of the  
Schneider Electric EVlink product line conducted by security professionals to  
identify and resolve potential further security issues.  
Vulnerability overview/description:  
1) Authentication Bypass with Undocumented Hard Coded Credentials (CVE-2021-22707)  
The authentication for the EVlink administration web interface can be bypassed  
with undocumented and hard coded HTTP cookie values. Initial analysis indicates  
that this authentication method is intended for local authentication by the  
"evse" service.  
2) Lack of Secure Update Mechanism / Remote Code Execution (CVE-2021-22708)  
An authenticated attacker can upload arbitrary, malicious firmware updates to  
the device and thus gain remote code execution. The firmware integrity is  
checked by generating a SHA256 hash of the firmware update contents and a hard  
coded value and comparing it against a hash stored within the firmware update  
(CONTROL file).  
An attacker can create a malicious firmware update by modifying the firmware  
contents and adjusting the hash in the CONTROL file.  
Based on public information we believe this vulnerability type was once  
reported as CVE-2018-7801 by Positive Technologies before.  
The patch notes [1] indicate that a signature was introduced in R6 software  
v3.2.0-12 as a fix. It is likely this fix did not actually fix the  
[1] <>  
Proof of concept:  
1) Authentication Bypass with Undocumented Hard Coded Credentials (CVE-2021-22707)  
The web interface authentication can be bypassed by setting the following HTTP  
cookie values:  
- CURLTOKEN=b35fcdc1ea1221e6dd126e172a0131c5a  
- SESSIONID=admin  
With those cookies the attacker is logged in with admin permissions.  
2) Lack of Secure Update Mechanism / Remote Code Execution (CVE-2021-22708)  
The file "" stored in /mnt/datas/opt/evse/ performs  
the validation of the firmware update image.  
Below is an excerpt:  
# extract files from archive (epz is an epk.gz, but tar xf will handle it)  
tar xf "$file"  
if [[ ! -f CONTROL ]]; then  
abort "KO, missing signature"  
echo $private_key > private  
find . -type f | grep -v CONTROL | xargs sha256sum | awk '{print $1}' | sort | sha256sum > ../CONTROL2  
mv ../CONTROL2 .  
rm private  
if [[ "`diff CONTROL CONTROL2`" != "" ]]; then  
abort "KO, signatures mismatch"  
The $private_key parameter is not a cryptographic signature. It is a hard coded  
key found in the "cgiServer" and "evse" binary and not a cryptographic  
The value is: 67acdb2bce676ac1b1766c99b07f37fa591ea5f39f57afc874bab704a0a36964  
It is placed in the firmware directory during the computation of the SHA256  
This script can be modified easily to provide a valid hash for the CONTROL  
Vulnerable / tested versions:  
The vulnerabilities have been found in the firmware R7 (Version V3.3.0.15),  
which is the latest version at the time of discovery.  
Initial analysis indicates that at least the following Schneider Electric  
products are affected:  
- EVlink Charging Smart Wallbox  
- EVlink Parking  
- EVlink City ranges  
Vendor contact timeline:  
2021-03-11 | Contacting vendor <>  
2021-03-11 | Vendor response, vulnerabilities are under investigation.  
2021-03-11 | Vendor response, vulnerabilities confirmed, fix and disclosure  
scheduled for July 2021.  
2021-07-14 | Coordinated release of security advisory.  
Update to the most recent firmware version provided on the vendor's website.  
Version R8 V3.4.0.1 includes a fix for the vulnerabilities.  
Further information can be found in the Schneider Electric security  
notification: <>  
Advisory URL:  
------------- <>  
SEC Consult Vulnerability Lab  
SEC Consult, an Atos company  
Europe | Asia | North America  
About SEC Consult Vulnerability Lab  
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Atos company. It ensures the continued knowledge gain of SEC Consult in the  
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the evaluation of new offensive and defensive technologies for our customers.  
Hence our customers obtain the most current information about vulnerabilities  
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EOF Stefan Viehböck / @2021