Bypassing the authentication for the MediaTek MT6789 (Helio G99) chip involves exploiting the Boot ROM (BROM) to disable security protocols like (Serial Link Authentication) and (Download Agent Authentication).

Professional Servicing Tools: If open-source methods fail, paid tools like the Hydra Tool or UnlockTool frequently update their databases with "DA" (Download Agent) and "Auth" files specifically for MT6789 devices (e.g., Helio G99 found in some Infinix, Tecno, and Samsung models). Step-by-Step Bypass Guide (MTKClient)

4. Impact Assessment

| Asset | Impact | |-------|--------| | Bootloader integrity | Bypassed – Secure Boot flag can be cleared. | | User data | Full physical extraction of /data partition, including encryption keys if stored in RPMB (vulnerable via preloader). | | Device persistence | Permanent rooting via modified boot.img or vbmeta. | | Supply chain | Attack can be weaponized in repair centers or second-hand market to pre-infect devices. |

Steps

  1. Extract preloader from firmware – Use mtkclient (patched version for MT6789) to dump preloader via BROM, bypassing the initial DMA protection.
  2. Analyze auth challenge logic – Locate the function handling sec_policy and signature check. On MT6789, this is inside pl_sec.c in preloader.
  3. Patch the challenge comparator – Instead of disabling auth entirely, flip the if (auth_result != 0) to if (auth_result == 0) in the check branch.
    This avoids triggering anti-tamper flags.
  4. Repack and flash preloader – Use SP Flash Tool with “DA bypass” option to write the patched preloader back without full authentication.
  5. Bypass remaining secure boot – After preloader accepts invalid signatures, the boot image can be replaced with a patched lkboot where ro.secure=0 is enforced.

As of 2026, the MT6789 remains a high-value target. While it is significantly more secure than its predecessors, researchers continue to find "leaks" in the armor.

Connection: Connecting the device in Preloader mode (often by simply plugging it in without pressing hardware buttons).