This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of D-Link DIR-1935 1.03 routers. Although authentication is required to exploit this vulnerability, the existing authentication mechanism can be bypassed. The specific flaw exists within the handling of ConfigFileUpload requests to the web management portal. The issue results from the lack of proper validation of a user-supplied string before using it as a format specifier. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-16141.
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Dir-1935_firmware | Dlink | * | 1.02 (including) |
| Dir-1935_firmware | Dlink | 1.03-b1 (including) | 1.03-b1 (including) |
| Dir-1935_firmware | Dlink | 1.03-b2 (including) | 1.03-b2 (including) |
When an attacker can modify an externally-controlled format string, this can lead to buffer overflows, denial of service, or data representation problems. It should be noted that in some circumstances, such as internationalization, the set of format strings is externally controlled by design. If the source of these format strings is trusted (e.g. only contained in library files that are only modifiable by the system administrator), then the external control might not itself pose a vulnerability.