CVE-2019-15803
An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0.
Impact
An issue was discovered on Zyxel GS1900 devices with firmware before 2.50(AAHH.0)C0. Through an undocumented sequence of keypresses, undocumented functionality is triggered. A diagnostics shell is triggered via CTRL-ALT-t, which prompts for the password returned by fds_sys_passDebugPasswd_ret(). The firmware contains access control checks that determine if remote users are allowed to access this functionality. The function that performs this check (fds_sys_remoteDebugEnable_ret in libfds.so) always return TRUE with no actual checks performed. The diagnostics menu allows for reading/writing arbitrary registers and various other configuration parameters which are believed to be related to the network interface chips.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Zyxel | Gs1900-8 Firmware | before 2.50\(aahh.0\)c0 |
| Zyxel | Gs1900-8hp Firmware | before 2.50\(aahi.0\)c0 |
| Zyxel | Gs1900-10hp Firmware | before 2.50\(aazi.0\)c0 |
| Zyxel | Gs1900-16 Firmware | before 2.50\(aahj.0\)c0 |
| Zyxel | Gs1900-24e Firmware | before 2.50\(aahk.0\)c0 |
| Zyxel | Gs1900-24 Firmware | before 2.50\(aahl.0\)c0 |
| Zyxel | Gs1900-24hp Firmware | before 2.50\(aahm.0\)c0 |
| Zyxel | Gs1900-48 Firmware | before 2.50\(aahn.0\)c0 |
| Zyxel | Gs1900-48hp Firmware | before 2.50\(aaho.0\)c0 |