CVE-2021-28838 in DAP-2310
Summary
by MITRE • 08/11/2021
Null pointer dereference vulnerability in D-Link DAP-2310 2,10RC039, DAP-2330 1.10RC036 BETA, DAP-2360 2.10RC055, DAP-2553 3.10rc039 BETA, DAP-2660 1.15rc131b, DAP-2690 3.20RC115 BETA, DAP-2695 1.20RC093, DAP-3320 1.05RC027 BETA and DAP-3662 1.05rc069 in the sbin/httpd binary. The crash happens at the `atoi' operation when a specific network package are sent to the httpd binary.
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Analysis
by VulDB Data Team • 08/15/2021
This vulnerability represents a critical null pointer dereference flaw in multiple D-Link wireless access point models including DAP-2310, DAP-2330, DAP-2360, DAP-2553, DAP-2660, DAP-2690, DAP-2695, DAP-3320, and DAP-3662. The issue manifests within the sbin/httpd binary component where the application fails to properly validate incoming network packets before processing them through the atoi function. This particular flaw falls under CWE-476 which specifically addresses null pointer dereference vulnerabilities, making it a direct implementation of a well-known security weakness pattern. The vulnerability is particularly concerning as it exists in the core web server component of these devices, indicating a fundamental lack of input sanitization and validation mechanisms.
The technical exploitation occurs when malformed network packets are transmitted to the affected devices, triggering a crash in the httpd binary process. During the processing of these packets, the atoi function attempts to convert string representations to integers but encounters a null pointer reference due to insufficient validation of the input data. This particular attack vector represents a classic denial of service scenario where an unauthenticated remote attacker can send specially crafted packets to cause the device to crash and potentially become unavailable to legitimate users. The vulnerability demonstrates poor defensive programming practices where the application assumes input data will always be properly formatted without proper null checking mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption as it affects a wide range of enterprise and consumer networking equipment. Organizations relying on these D-Link access points for network infrastructure may experience service interruptions, particularly in environments where continuous network availability is critical. The vulnerability affects multiple generations of D-Link access points, suggesting a systemic issue in the software development lifecycle where input validation was not properly implemented across the affected product line. From an attacker perspective, this represents a low-effort, high-impact method for causing network disruption, as it requires only the ability to send network packets to the target device without requiring any authentication credentials.
Mitigation strategies should focus on immediate firmware updates from D-Link to address the root cause of the vulnerability. Network administrators should implement network segmentation and monitoring to detect unusual packet patterns that may indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and organizations should consider implementing intrusion detection systems to monitor for such patterns. Additionally, implementing proper input validation mechanisms at the application level, including bounds checking and null pointer verification before calling atoi or similar functions, would prevent this class of vulnerability from occurring. Organizations should also consider network-level protections such as rate limiting and packet filtering to reduce the impact of potential exploitation attempts against these vulnerable devices.