如何在十六进制转储中定位汇编代码并修改以绕过Dock固件检测

Let's break down how to properly bypass the external display detection blocking your firmware rollback, using the disassembly and hex dump you provided.

Key Analysis of the Assembly Code #

The critical display check happens right after calling the detection function SUB_L00403700:

00403C03 E8F8FAFFFF call SUB_L00403700  ; Triggers external display detection
00403C08 85C0 test eax,eax              ; Checks if detection succeeded (eax=0) or failed (eax≠0)
00403C0A 7433 jz L00403C3F              ; Jumps to normal rollback flow ONLY if detection passes

Since your dock's display port is damaged, SUB_L00403700 returns a non-zero error value. The original jz instruction won't trigger, so the program gets stuck in the error branch instead of proceeding with the rollback.

Why Your Previous Modifications Didn't Work #

• Changing 75 07 to 75 33: This modified a secondary check (jnz L00403C1B) deep in the error branch, not the core display detection gate. It didn't bypass the main block.
• Changing 74 33 to 75 33: This reversed the jump condition to jnz (jump if not zero), but the detection function's error return value might have broken subsequent validation steps, causing the hang you saw.

Correct Hex Modification to Bypass Detection #

Instead of reversing the jump logic, force an unconditional jump to the normal rollback flow, ignoring the detection result entirely:

1. In your HxD hex dump, locate the sequence 85 C0 74 33 (this maps to the test eax,eax and jz L00403C3F instructions in the disassembly).
2. Replace the 74 33 (hex for jz short L00403C3F) with EB 33 (hex for jmp short L00403C3F).

This modification tells the program to skip the error branch entirely and proceed directly to the firmware rollback process, no matter if a display is detected or not.

Critical Pre/Post Steps #

• Backup First: Always make a copy of the original firmware executable before modifying it. If something goes wrong, you can revert immediately.
• Validate the Offset: Double-check that you're modifying the exact 74 33 at memory address 00403C0A (match it to your disassembly to avoid editing the wrong instruction).
• Post-Modification Checks: If the dock still stays bricked after this change, there may be additional hardware checks (like power status validation around GetSystemPowerStatus) blocking the process. Review the surrounding code to ensure those checks aren't failing for your bricked dock.

内容的提问来源于stack exchange，提问作者user20121217