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rohan [2017/10/01 19:23] (current)
daeken created
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 +ROhan is an exploit to enable userland arbitrary code execution on Switch OS 3.0.  It works due to Nintendo’s code making a number of assumptions that don’t hold when sm:h is in play:
 +
 +  * With OS 3.0.0, Nintendo split the ldr:ro service away from the ldr sysmodule, in an attempt to limit the attack surface of the critical ldr.
 +  * The newly-created RO sysmodule contains a codepath meant to ease testing for use on devkits: when loading in NRR files (which validate the integrity of NRO "​dlls"​),​ the module will contact the spl: service to check the IsDebugMode flag, and contact the settings sysmodule to request the ro!ease_nro_restriction setting. If both of these are set, the signature check is skipped.
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 +Both of these changes mark theoretical improvements to the system'​s security. However, sm:h grants full access to the services API -- including both registering and unregistering existing services. As such, the exploit flow looks like this:
 +
 +  - Set the ro!ease_nro_restriction setting to 1
 +  - Using a compromised sysmodule (more on this later), MITM the spl: service to cause any GetConfig call of type 0xb (IsDebugMode) to return 1
 +  - Kill and relaunch ro
 +  - Load any unsigned nrr
 +  - Load any nro whose hash exists in that nrr
 +
 +The reason we need a compromised sysmodule is that the ReplyAndReceive syscall, required to imitate a service, simply doesn’t exist in the browser. ​ As such, we hijack an existing sysmodule to perform this attack.
 +
 +In 3.0, the sdb sysmodule contains a number of bugs that make it a prime target. ​ We currently have an arbitrary write and control of the execution flow; what we don’t have is an actual ROP/​JOP-chain to allow arbitrary function calling. ​ This is the sole piece missing for userland ACE on the Switch.
  
rohan.txt · Last modified: 2017/10/01 19:23 by daeken