An issue exists on Zyxel GS1900 devices with firmware prior to 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.
| Vulnerable Product | Search on Vulmon | Subscribe to Product |
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zyxel gs1900-8_firmware |
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zyxel gs1900-8hp_firmware |
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zyxel gs1900-10hp_firmware |
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zyxel gs1900-16_firmware |
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zyxel gs1900-24e_firmware |
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zyxel gs1900-24_firmware |
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zyxel gs1900-24hp_firmware |
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zyxel gs1900-48_firmware |
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zyxel gs1900-48hp_firmware |
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