CWE-1251: Mirrored Regions with Different Values

What is Mirrored Regions with Different Values?

• Overview: Mirrored Regions with Different Values (CWE-1251) is a vulnerability where the architecture of a system mirrors certain regions (like memory or registers) but fails to ensure that their contents are consistently synchronized. This can lead to discrepancies where the mirrored copies have different data than the original, potentially exposing sensitive information or allowing unauthorized actions.

• Exploitation Methods:

• Attackers can exploit this vulnerability by targeting the synchronization process between the original and mirrored regions.
• Common attack patterns include intercepting update requests, exploiting race conditions where the mirrored copy is updated slower than the original, and sending spoofed update requests to change mirrored values maliciously.

• Security Impact:

• Direct consequences of successful exploitation include data leakage, unauthorized access to resources, and potential system compromise.
• Potential cascading effects might include further exploitation of inconsistent data states and the propagation of corrupted data throughout the system.
• Business impact can be significant, involving loss of data integrity, breach of sensitive information, regulatory penalties, and damage to reputation.

• Prevention Guidelines:

• Specific code-level fixes include implementing robust synchronization mechanisms that ensure updates are applied to all mirrored copies immediately and reliably.
• Security best practices involve regular audits of data synchronization processes, implementing error-checking routines, and ensuring that update mechanisms are secure from interception or spoofing.
• Recommended tools and frameworks include those that facilitate real-time monitoring of mirrored regions and provide automated alerts for synchronization discrepancies, as well as using secure communication protocols for update transmissions.

Corgea can automatically detect and fix Mirrored Regions with Different Values in your codebase. [Try Corgea free today](https://corgea.app).

Technical Details

Likelihood of Exploit: Not specified

Affected Languages: VHDL, Verilog

Affected Technologies: System on Chip

Vulnerable Code Example

Certainly! Here is the improved content with the necessary corrections and enhancements:

-- Vulnerable code demonstrating CWE-1251: Mirrored Regions with Different Values
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity MemoryController is
    Port ( clk : in STD_LOGIC;
           write_enable : in STD_LOGIC;
           address : in INTEGER;
           data_in : in STD_LOGIC_VECTOR (7 downto 0);
           data_out_a : out STD_LOGIC_VECTOR (7 downto 0);
           data_out_b : out STD_LOGIC_VECTOR (7 downto 0));
end MemoryController;

architecture Behavioral of MemoryController is
    type memory_array is array (0 to 255) of STD_LOGIC_VECTOR (7 downto 0);
    signal memory_a : memory_array := (others => (others => '0'));
    signal memory_b : memory_array := (others => (others => '0')); -- Mirrored region

begin
    process(clk)
    begin
        if rising_edge(clk) then
            if write_enable = '1' then
                memory_a(address) <= data_in;
                -- Missing synchronization for mirrored memory_b
            end if;
            data_out_a <= memory_a(address);
            data_out_b <= memory_b(address); -- Independent read from unsynchronized memory_b
        end if;
    end process;
end Behavioral;

Explanation of Vulnerability

The above code contains a vulnerability where memory_a and memory_b are intended to be mirrored regions (i.e., they should always contain the same data). However, the write operation only updates memory_a, leaving memory_b unsynchronized. This can cause inconsistent data reads from memory_b, which violates the mirrored regions' integrity.

How to fix Mirrored Regions with Different Values?

Fixed Code Example

-- Fixed code with synchronization to ensure mirrored regions have consistent data
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity MemoryController is
    Port ( clk : in STD_LOGIC;
           write_enable : in STD_LOGIC;
           address : in INTEGER;
           data_in : in STD_LOGIC_VECTOR (7 downto 0);
           data_out_a : out STD_LOGIC_VECTOR (7 downto 0);
           data_out_b : out STD_LOGIC_VECTOR (7 downto 0));
end MemoryController;

architecture Behavioral of MemoryController is
    type memory_array is array (0 to 255) of STD_LOGIC_VECTOR (7 downto 0);
    signal memory_a : memory_array := (others => (others => '0'));
    signal memory_b : memory_array := (others => (others => '0'));

begin
    process(clk)
    begin
        if rising_edge(clk) then
            if write_enable = '1' then
                memory_a(address) <= data_in;
                memory_b(address) <= data_in; -- Synchronize mirrored region
            end if;
            -- Ensure consistent reads by reading from synchronized regions
            data_out_a <= memory_a(address);
            data_out_b <= memory_b(address);
        end if;
    end process;
end Behavioral;

Explanation of the Fix

In the fixed code, when write_enable is high, both memory_a and memory_b are updated with the data_in value. This ensures that both mirrored regions are synchronized, maintaining consistent data integrity across reads. By ensuring atomic updates to both memory regions, the CWE-1251 vulnerability is mitigated.

Best Practices

• Synchronization: Always synchronize mirrored data regions during write operations to prevent inconsistent data states.
• Atomic Operations: Use atomic operations to ensure data consistency across mirrored regions.
• Consistent Read: Ensure that read operations are consistent and reflect the synchronized state of mirrored regions.

This revised content addresses the initial issues, ensuring that the examples are clear, realistic, and adhere to VHDL best practices.