Post B99iRMraedUEYdOqgK by never_released@mastodon.social
 (DIR) More posts by never_released@mastodon.social
 (DIR) Post #B99b0upNZIzoOknymO by ariadne@social.treehouse.systems
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       so bootrom goes into xbl, which then boots gunyah and then gunyah boots the lenovo bios, humm
       
 (DIR) Post #B99b5DnqxbQEPL91yC by ariadne@social.treehouse.systems
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       sure wish i had one of those hack anything models right about now, so it could tell me that they take cybersecurity very seriously and then proceed to not find an xbl exploit so i can coreboot this fucker
       
 (DIR) Post #B99bC7sxMPoY56p9LU by ariadne@social.treehouse.systems
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       oh don't you worry, i'm a security researcher with a grudge
       
 (DIR) Post #B99bHbc2GOIjj5WRAu by ariadne@social.treehouse.systems
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       i wonder if i could build a harness to fuzz the everloving hell out of xbl with qemu
       
 (DIR) Post #B99bLk6MdufjDHgGzQ by ariadne@social.treehouse.systems
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       and no, i won't be reporting anything i find to qualcomm, they can go fuck themselves
       
 (DIR) Post #B99bOrrWFI4K9QE9mi by ariadne@social.treehouse.systems
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       if you want security researchers to be nice, don't participate in selling them defective equipment
       
 (DIR) Post #B99cKkUZnzEo5a60no by ariadne@social.treehouse.systems
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       xbl is not particularly complex.  it starts TEE (their take on trustzone basically), which then starts gunyah.TEE is stored in flash...
       
 (DIR) Post #B99cWwr3fQQHuEQdns by ariadne@social.treehouse.systems
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       i wonder if TEE configuration can be adjusted in some way to just bypass gunyah entirely...but i bet you they've done something nasty like sign the configuration blob
       
 (DIR) Post #B99cfNErSLcu3Da1NQ by ariadne@social.treehouse.systems
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       current conclusions: don't need to fuzz xbl, but maybe the TEE initialization procedure is worth fuzzingagain, i'm a security researcher with a grudge
       
 (DIR) Post #B99iRMraedUEYdOqgK by never_released@mastodon.social
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       @ariadne yes it can there's a bit just for this in xbl_configAlthough not sure that the shipped fw baseline is new enough on those thingsYou can look at Hamoa IoT EVK firmware that has the newer one with EL2 compiled in
       
 (DIR) Post #B99mjvqzhQ426jEEm8 by philpem@digipres.club
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       @ariadne ah, a bootloader lilypond.
       
 (DIR) Post #B99t22Zw2CuVtyGdgO by freya@social.highenergymagic.net
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       @ariadne xbl is such a fucking mess. *such* a fucking mess. one of those fucking UFS partitions on that laptop has strings for a Linux 3.x kernel in it for some reason
       
 (DIR) Post #B9A8tKlWe3vKy4Yifo by cas@social.treehouse.systems
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       @ariadne what soc r u looking at?the general bootflow is that the brom loads the nested xbl_sec.elf (which is an elf inside a load section of xbl) that provides a barebones el3 which calls into the bootroms signature validation helpersthen XBLLoader (aka sbl1) runs in EL1 and makes SMC calls to start the aop, tz, hyp, etc (xbl_sec checks the signing)on sc8280xp and x1e there's the hyp exploit to gain el2, on qcs6490 there's an SMC call to gain EL2 and more recently qualcomm published a modified xbl_sec that disables the qcom signature requirement of tz so you can build and flash TF-A
       
 (DIR) Post #B9ALO2OaC3LUQBEcQS by ariadne@social.treehouse.systems
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       @cas x1e