CWE-1419: Incorrect Initialization of Resource

How it's found

Incorrect Initialization of Resource describes a general pattern rather than a single fixed bug. Testers use a mix of static analysis and manual code review to find where a target's code matches this pattern, then confirm exploitability by hand.

This can have security implications when the associated resource is expected to have certain properties or values. Examples include a variable that determines whether a user has been authenticated or not, or a register or fuse value that determines the security state of the product. For software, this weakness can frequently occur when implicit initialization is used, meaning the resource is not explicitly set to a specific value. For example, in C, memory is not necessarily cleared when it is allocated on the stack, and many scripting languages use a default empty, null value, or zero value when a variable is not explicitly initialized. For hardware, this weakness frequently appears with reset values and fuses. After a product reset, hardware may initialize registers incorrectly. During different phases of a product lifecycle, fuses may be set to incorrect values. Even if fuses are set to correct values, the lines to the fuse could be broken or there might be hardware on the fuse line that alters the fuse value to be incorrect.

Vulnerable vs. safe

Data_out <= REGISTER_DEFAULT; // Register content set to Default at resetSecure_mode <= REGISTER_DEFAULT[0]; // Register Secure_mode set at reset

Data_out <= Data_in;if (~resetn)beginendelse if (write & ~Secure_mode)beginend

.REGISTER_WIDTH (32),.REGISTER_DEFAULT (1224) // Incorrect Default value used bit 0 is 0.

.Data_in (Data_in),.Data_out (Secure_reg),.Clk (Clk),.resetn (resetn),.write (write)

.REGISTER_WIDTH (32) // Default not defined 2^32-2 value will be used as default.

.Data_in (Data_in),.Data_out (Insecure_reg),.Clk (Clk),.resetn (resetn),.write (write)// Parameterized Register module example// Secure_mode : REGISTER_DEFAULT[0] : When set to 1 register is read only and not writable//module register_example#(parameter REGISTER_WIDTH = 8, // Parameter defines width of register, default 8 bitsparameter [REGISTER_WIDTH-1:0] REGISTER_DEFAULT = 2**REGISTER_WIDTH -2 // Default value of register computed from Width. Sets all bits to 1s except bit 0 (Secure _mode))(input [REGISTER_WIDTH-1:0] Data_in,input Clk,input resetn,input write,output reg [REGISTER_WIDTH-1:0] Data_out);reg Secure_mode;always @(posedge Clk or negedge resetn)endmodulemodule register_top(input Clk,input resetn,input write,input [31:0] Data_in,output reg [31:0] Secure_reg,output reg [31:0] Insecure_reg);register_example #() Insecure_Device_ID_1 ();register_example #() Insecure_Device_ID_2 ();endmodule

.REGISTER_WIDTH (32),.REGISTER_DEFAULT (1225) // Correct default value set, to enable Secure_mode

.Data_in (Data_in),.Data_out (Secure_reg),.Clk (Clk),.resetn (resetn),.write (write)register_example #() Secure_Device_ID_example ();

Consequences

• Read Memory, Read Application Data, Unexpected State
• Gain Privileges or Assume Identity
• Varies by Context: The technical impact can vary widely based on how the resource is used in the product, and whether its contents affect security decisions.

Mitigations

• Implementation: Choose the safest-possible initialization for security-related resources.
• Implementation: Ensure that each resource (whether variable, memory buffer, register, etc.) is fully initialized.
• Implementation: Pay close attention to complex conditionals or reset sources that affect initialization, since some paths might not perform the initialization.
• Architecture and Design: Ensure that the design and architecture clearly identify what the initialization should be, and that the initialization does not have security implications.

Where this fits in a TurboPentest engagement

This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.

Frequently asked questions

Related CWEs

• Class weakness
  CWE-665: Improper Initialization