Description Preview
A stack-based buffer overflow vulnerability exists in the do_cgi() function of D-Link DSL-2640B B2 EU_4.01B devices. This function processes CGI requests sent to the device's web servers and fails to properly validate input, leading to a buffer overflow condition. When exploited, this vulnerability could allow an attacker to execute arbitrary code with the privileges of the web server process. While authentication is normally required, this vulnerability can be exploited by unauthenticated attackers when combined with the authentication bypass vulnerability tracked as CVE-2020-9277.
Overview
The D-Link DSL-2640B router contains a critical vulnerability in its web interface that processes CGI requests. The do_cgi() function improperly handles user input, allowing attackers to overflow a stack buffer and potentially execute arbitrary code on the device. This vulnerability affects D-Link DSL-2640B B2 devices running firmware version EU_4.01B. The vulnerability is classified as CWE-787 (Out-of-bounds Write), which can lead to memory corruption, device crashes, or complete takeover of the affected system. When combined with the authentication bypass vulnerability (CVE-2020-9277), unauthenticated attackers can remotely exploit this issue, making it particularly dangerous.
Remediation
- Check if your D-Link DSL-2640B router is running firmware version EU_4.01B.
- Visit the D-Link Security Bulletin website (https://www.dlink.com/en/security-bulletin) to check for firmware updates that address this vulnerability.
- Apply any available security patches or firmware updates as soon as possible.
- If no patches are available, consider implementing the following mitigations:
- Restrict access to the router's web interface to trusted IP addresses only.
- Use a firewall to block external access to the router's management interface.
- Consider replacing the router with a newer, supported model if no security updates are available.
- Regularly check for and apply firmware updates to ensure your device has the latest security patches.
References
- Raelize Advisory: https://raelize.com/advisories/CVE-2020-9276_D-Link-DSL-2640B_do_cgi-buffer-overflow_v1.0.txt
- Raelize Blog Post: https://raelize.com/posts/d-link-dsl-2640b-security-advisories/
- D-Link Security Bulletin: https://www.dlink.com/en/security-bulletin
- MITRE CWE-787: https://cwe.mitre.org/data/definitions/787.html
- Related vulnerability: CVE-2020-9277 (Authentication Bypass)
Industry ExposureMost to leastThis section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.
This section illustrates the prevalence of a specific Common Vulnerabilities and Exposures (CVE) across various industries based on customer reports. The ranking displays industries from the most to least affected by this particular vulnerability, offering valuable insight into where this CVE has been most frequently observed. This information can help organizations within these sectors prioritize their security efforts, understand their relative risk exposure compared to their peers, and focus remediation strategies where they are most needed. By understanding the industry-specific impact, organizations can make more informed decisions regarding patching, resource allocation, and overall risk management related to this CVE.
- Accommodation & Food ServicesAccommodation & Food Services
- Administrative, Support, Waste Management & Remediation ServicesAdministrative, Support, Waste Management & Remediation Services
- Agriculture, Forestry Fishing & HuntingAgriculture, Forestry Fishing & Hunting
- Arts, Entertainment & RecreationArts, Entertainment & Recreation
- ConstructionConstruction
- Educational ServicesEducational Services
- Finance and InsuranceFinance and Insurance
- Health Care & Social AssistanceHealth Care & Social Assistance
- InformationInformation
- Management of Companies & EnterprisesManagement of Companies & Enterprises
- ManufacturingManufacturing
- MiningMining
- Other Services (except Public Administration)Other Services (except Public Administration)
- Professional, Scientific, & Technical ServicesProfessional, Scientific, & Technical Services
- Public AdministrationPublic Administration
- Real Estate Rental & LeasingReal Estate Rental & Leasing
- Retail TradeRetail Trade
- Transportation & WarehousingTransportation & Warehousing
- UtilitiesUtilities
- Wholesale TradeWholesale Trade
