Authentication Bypass Using an Alternate Path or Channel
This vulnerability occurs when a system has a primary login requirement, but attackers can find an unprotected backdoor or alternative route that completely bypasses those checks.
Think of it like a building with a guarded front door but an unlocked side window. The main application flow correctly validates user credentials, but developers might overlook a secondary API endpoint, a hidden administrative page, a debug interface, or a direct file path that doesn't enforce the same authentication rules. Attackers discover these alternate channels through reconnaissance, fuzzing, or analyzing application structure, allowing them to access restricted functions or data without ever logging in. This often happens during development when temporary access points are created for testing and never removed, or when different system components have inconsistent security policies. To prevent it, you must ensure every single entry point into protected functionality—including APIs, files, and hidden directories—enforces the same robust authentication checks. Regular security audits should map all access paths and verify none provide a secret bypass to your core security gate.
Impact: Bypass Protection Mechanism
ID : DX-176
Register SECURE_ME is located at address 0xF00. A mirror of this register called COPY_OF_SECURE_ME is at location 0x800F00. The register SECURE_ME is protected from malicious agents and only allows access to select, while COPY_OF_SECURE_ME is not. Access control is implemented using an allowlist (as indicated by acl_oh_allowlist). The identity of the initiator of the transaction is indicated by the one hot input, incoming_id. This is checked against the acl_oh_allowlist (which contains a list of initiators that are allowed to access the asset). Though this example is shown in Verilog, it will apply to VHDL as well.Code Example:
module foo_bar(data_out, data_in, incoming_id, address, clk, rst_n); output [31:0] data_out; input [31:0] data_in, incoming_id, address; input clk, rst_n; wire write_auth, addr_auth; reg [31:0] data_out, acl_oh_allowlist, q; assign write_auth = | (incoming_id & acl_oh_allowlist) ? 1 : 0; always @*
verilogCode Example:
assign addr_auth = (address == 32'hF00) ? 1: 0;
Code Example:
assign addr_auth = (address == 32'hF00 || address == 32'h800F00) ? 1: 0;
- PLOVER
- OWASP Top Ten 2007