neXus
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Posts posted by neXus
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Works fine here too with my module. I was digging on the disassembly code to check what was really checked.
Vortex is faster than me
I have some issue with my coredump as there is no symbols on it. I'm not a professional so I have to make it step by step. -
Ok, my hooking kernel module is almost ready, now we have to find the /proc/bus/pci/devices to feed it.
I tried why an handcrafted one, no luck
DiskStation> cat /proc/bus/pci/devices | openssl dgst -sha1 (stdin)= 0420d5aff0e976362758ec21d0d7e6def6730921 DiskStation> cat /root/devices | openssl dgst -sha1 (stdin)= 5d901113beb9d0b2a0ca458693d20a5697951c4e DiskStation> insmod dsmcheck.ko DiskStation> cat /proc/bus/pci/devices | openssl dgst -sha1 (stdin)= 5d901113beb9d0b2a0ca458693d20a5697951c4e
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This the site I was talking about :
http://arcane-labratory.blogspot.ro/sea ... 0antivirus
No sources / no binaries to use.
(I have read all of theses paper, if you can spend some time to find / try to unpack binaries, it could be useful).
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I don't find any, I cam across AVU but there is no source / binary available.
You can digg on it, could be usefull
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inside himself I believe as the binaries are packed. This could make sense.
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include long ptrace(int x, int y, int z) { printf("--this is the ptrace clone block--\n"); return 0; }Use it with strace -E LD_PRELOAD=./shareobject.so
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LD_PRELOAD the ptrace function as they check if the process is beeing debugged or straced.
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It's not working, I'm pretty sure the sanity check code is also in packed binaries (elf/cgi).
I kill everything (httpd/scemd/findhostd).
Changing as you said, fire a trace log on scemd launch, here is the result.
DiskStation> cat trace.7414 |grep open | grep cgi [f71acd6b] open("/usr/syno/synoman/webman/modules/StorageManager/storagehandler.cgi", O_RDONLY) = 11 [f71acd6b] open("/usr/syno/synoman/webman/modules/StorageManager/volumehandler.cgi", O_RDONLY) = 11 [f71acd6b] open("/usr/syno/synoman/webman/modules/PkgManApp/PkgMan.cgi", O_RDONLY) = 11 [f71acd6b] open("/usr/syno/synoman/webman/modules/PkgManApp/PkgSynoMan.cgi", O_RDONLY) = 11 [f71acd6b] open("/usr/syno/synoman/webman/modules/DSMNotify/dsmnotify.cgi", O_RDONLY) = 11 [f71acd6b] open("/lib/libsynocgi.so", O_RDONLY) = 11 DiskStation> strings /lib/libdsm.so.4 |grep .cgi /LIB/libsynocgi.so /USR/syno/synoman/webman/modules/StorageManager/storagehandler.cgi /USR/syno/synoman/webman/modules/StorageManager/volumehandler.cgi /USR/syno/synoman/webman/modules/PkgManApp/PkgMan.cgi /USR/syno/synoman/webman/modules/PkgManApp/PkgSynoMan.cgi /USR/syno/synoman/webman/modules/DSMNotify/dsmnotify.cgi -
Hu, not sure how it will be fooled, as /usr and /USR are distincts on case sensitive file system.
The only way to make it work could be to override /usr by /USR for the entire system (same for lib). As in binaries it looks for /usr /lib we can place orignal files in here. But it's really a dirty way !
EDIT : It may work in fact... give a try on it
But you can make a try and report
I preferrer not altering anything on stock firmware and make the work kernel side only. (Included synobios.ko I have plan for this one too).
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I dont understand what you mean...
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This will not work as an integrity check is done BEFORE parsing the devices.
Signature for elf/cgi are the same, same for the two so as well.
So there is two kind of hashes, I don't really know what is hashed.
There two hashes because elf/cgi are packed but not the so.
I have to find the common parts on each which I believe include the strings statements.
Another way will be modify the kernel sources to add the convenient devices but I don't know if there will be side effects.
Edit : better create a module which will hook open syscall and return a fake device list if it match some criteria.
Anyway a /proc/bus/pci/devices from a genuine 3612xs will be helpfull
So, maybe we don't need to patch files, proper simulation may do the trick.
Thanks
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So, I may have found how they protect it, no how to defeat it. Here is the deal.
Those files :
- /usr/syno/bin/findhostd
/usr/syno/bin/scemd
/lib/libdsm.so
/lib/libsynocgi.so
/usr/syno/synoman/webman/modules/StorageManager/storagehandler.cgi
/usr/syno/synoman/webman/modules/StorageManager/volumehandler.cgi
/usr/syno/synoman/webman/modules/PkgManApp/PkgMan.cgi
/usr/syno/synoman/webman/modules/PkgManApp/PkgSynoMan.cgi
/usr/syno/synoman/webman/modules/DSMNotify/dsmnotify.cgi
are packed the same way (I don't know yet if it's a home made packing or "readytogo" one.
Something is triggering sort of "sanity check" function.
At the end of each file above you can found a 256o chain, which is, I believe a RSA signature. So all theses files are checked to see if their integrity has not been compromised (with the dnsdsm cert). Expect the one which is running this function (here we found our /proc/self/comm string).
Once this santity check is done, another function open the synoinfo.conf to get the NAS unique model name, let's say synology_bromolow_3612xs.
It next open /proc/bus/pci/devices and check all the devices in it for I think a match with devices defined on each protected files above :
extract :
--------------------- Strings 808610d3 // 82574L Gigabit Network Connection e1000e 0b00 0c00 0d00 0100 --------------------- Strings
We can read thoses string as : 808610d3 pci id for the hardware / e1000e module associated / 0b00..0100 is the BusDevFunc id.
So I believe that somewhere, there is a link between the model and the following devices (ata/usb/ethernet).
if there is a mistmatch with this mapping, the process unlink (remove) /dev/sd* or /dev/sas*.
We can't alter the files without resign them with the private key associated with the dnsdsm cert and append the new signatures to the end of the file.
- /usr/syno/bin/findhostd
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197 [f6ec11f8] stat64("/dev/sda", {st_dev=makedev(9, 0), st_ino=712, st_mode=S_IFBLK|0644, st_nlink=1, st_uid=0, st_gid=0, st_blksize=4096, st_blocks=0, st_rdev=makedev(8, 0), st_atime=2013/09/23-16:45:50, st_mtime=2013/09/23-16:45:50, st_ctime=2013/09/23-16:45:50}) = 0 7197 [f6ec335d] unlink("/dev/sda") = 0One step beyond
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Interesting ARM firmware are not protected, no traces of obfuscation too. So it's clearly against xpenology
dnsdsm is clearly involved in the process, removing it and DSM said the root volume has crashed.
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Well, beta files are not packed but they don't seems to have any protection in it (no /dev/sd*).
One more thing, attaching strace to all http process, the cgi don't remove the sda, I believe so there is also countermeasure against dynamic analysis. (PTRACE detection pretty simple to do in fact.. damn... same for gdb)
20954 19:03:31 [f6bf4c08] ptrace(PTRACE_TRACEME, 0, 0, 0) = -1 EPERM (Operation not permitted) 20989 19:03:38 [f6c06c08] ptrace(PTRACE_TRACEME, 0, 0, 0) = -1 EPERM (Operation not permitted)
Hopefully it can be defeated
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Interesting binary are "packed", so we need to find how to depack them before process them.
I tryied generate a core dump by attaching GDB and use gcore, there is a lot to look inside.
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Ok I can now start a dynamic analysis, first thing I found :
I try to trace cgi execution, and create a mknod /dev/sda
I have no traces of storagehandler.cgi, it presume the check is done in several modules could be rsrcmonitor or externaldevices.
I'll keep trying, a little help could be fine
Sda Still here : 1379691942 16652 root 21600 S /usr/syno/synoman/webman/modules/ResourceMonitor/rsrcmonitor2.cgi Sda Still here : 1379691942 16652 root 21600 S /usr/syno/synoman/webman/modules/ResourceMonitor/rsrcmonitor2.cgi Sda Still here : 1379691946 23147 root 22748 S /usr/syno/synoman/webman/modules/SystemInfoApp/SystemInfo.cgi 23149 root 17724 S /usr/syno/synoman/webman/modules/PollingTask/polling.cgi 23236 root 23108 R /usr/syno/synoman/webman/modules/ControlPanel/modules/externaldevices.cgi Sda Still here : 1379691947 23219 root 18104 S /usr/syno/synoman/webman/modules/SystemInfoApp/LogViewer.cgi 24752 root 21600 S /usr/syno/synoman/webman/modules/ResourceMonitor/rsrcmonitor2.cgi Sda Still here : 1379691950 27243 root 17636 R /usr/syno/synoman/webman/modules/DSMNotify/dsmnotify.cgi no more sda : 1379691950 27243 root 17768 S /usr/syno/synoman/webman/modules/DSMNotify/dsmnotify.cgi
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Any way, Is there anyone with a genuine Synology to just dump and share some information.
I will need
i2cdetect -l
i2cdetect -y 0
Try to find addresses of i2c devices (number located on the table)
and
i2cdump -y 0
Thanks !
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Giving up for now static analysis, I will make my custom kernel with debug enabled and start dynamic analysis.
Obfuscation is pretty hard to read, that's the point of this
Anyway, seems the cgi don't have any obfuscation, how did you manage to get the core ? (Not familliar with web stuff
)Thanks
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As far as I know there are non senses obfuscation :
loc_4ACF8: ; CODE XREF: LOAD:loc_4ACF8p LOAD:0004ACF8 E8 FC FF FF FF call near ptr loc_4ACF8+1
You can found the pattern "E8 FC FF FF FF" regulary on this bloc of code.
I made a little script to undefine this as there is non sens for me.
def fixTheJmpCalls(): # Fix the jmp call in select code selection, startaddr, endaddr = idaapi.read_selection() idaapi.unmark_selection() if selection: for opcode in range(startaddr,endaddr): if GetMnem(opcode) == "jmp" or GetMnem(opcode) == "call": if GetDisasm(opcode)[-2:-1] == "+" and GetDisasm(opcode)[-1:].isdigit(): print "Broken Instruction: %X"%opcode, GetDisasm(opcode) MakeUnkn(opcode,0) MakeArray(opcode,5)it seems to fix the flow, but there are still some other obfuscation to reveal, example :
loc_4AE00: ; CODE XREF: LOAD:0004ADF6j LOAD:0004AE00 8B 8D 9C F8 FF FF mov ecx, [ebp-764h] LOAD:0004AE06 85 C9 test ecx, ecx LOAD:0004AE08 74 0E jz short loc_4AE18 LOAD:0004AE0A 8B 85 9C F8 FF FF mov eax, [ebp-764h] LOAD:0004AE10 89 04 24 mov [esp], eax LOAD:0004AE13 LOAD:0004AE13 loc_4AE13: ; CODE XREF: LOAD:loc_4AE13p LOAD:0004AE13 E8 FC FF FF FF call near ptr loc_4AE13+1 LOAD:0004AE18 LOAD:0004AE18 loc_4AE18: ; CODE XREF: LOAD:0004AE08j LOAD:0004AE18 85 DB test ebx, ebx
The test eax,eax will always be true, so the jz will always jump and the code behind never used. It could be changes to :
LOAD:0004AE00 loc_4AE00: ; CODE XREF: LOAD:0004ADF6j LOAD:0004AE00 8B 8D 9C F8 FF FF mov ecx, [ebp-764h] LOAD:0004AE06 85 C9 test ecx, ecx LOAD:0004AE08 74 0E jz short loc_4AE18 LOAD:0004AE08 ; --------------------------------------------------------------------------- LOAD:0004AE0A 8B 85 9C F8 FF FF 89 04 24 E8+junk db 'ïࣰ ë',4,'$Þ³ ' LOAD:0004AE18 ; --------------------------------------------------------------------------- LOAD:0004AE18 LOAD:0004AE18 loc_4AE18: ; CODE XREF: LOAD:0004AE08j
Not sure it will help but I don't found any other explanation.
Assembly guys, please contribute
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I came accross this one too but it only traverse defined func. It seems there is a mix of several obfuscation in here. The good point I think, the harder they try to hide what is done, easier it will be to fool once we figure out what is really done
I'm working on the libdsm.so as it has the same pattern as cgi regarding obfuscation. I will share any progress here, do the same
I have change a bit the python code to work on selected area :
def fixTheJmpCalls(): # Fix the jmp call in select code selection, startaddr, endaddr = idaapi.read_selection() if selection: for opcode in range(startaddr,endaddr): if GetMnem(opcode) == "jmp" or GetMnem(opcode) == "call": if GetDisasm(opcode)[-2:-1] == "+" and GetDisasm(opcode)[-1:].isdigit(): print "Broken Instruction: %X"%opcode, GetDisasm(opcode) code_addr = GetOperandValue(opcode, 0) fix_addr = code_addr -1 MakeUnkn(fix_addr,1) MakeCode(code_addr)I'll give a try
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Disassembly code contains anti reverse technique (Jump Trick with short near ptr loc+1) in order to avoid linear disassembly :
33 C0 XOR eax, eax
74 01 jz short near ptr loc+1
E9 58 C3 68 94 jmp near ptr 94A8D521h
Should be disassembled as :
33 C0 xor eax,eax
74 01 jz short near ptr loc+1
E9 junk
58 Pop eax
C3 retn
It will be harder to find what is really done. It's the same countermeasure malware uses.
More info here :
http:http://books.google.fr/books?id=FQC8EPYy834C&lpg=PA329&ots=BsntpxIe6l&dq=Fool%20Linear%20Disassembly&hl=fr&pg=PA329#v=onepage&q=Fool%20Linear%20Disassembly&f=false
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Could be dumb question but :
Someone with a silicon raid controller can give a try ? As it seems too be a common factor.
What happens if we use only pata disks (/dev/hdX) ?
The test seems in call near ptr dword_F6BB419C, we have to study it
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@Andy928,
From where did you get the stage2 grub file, I guess stage1 & 1.5 are almost "regular" but there are a lot of feature in stage2 added by Syno.
I was also wondering why we could not find sources for the modified grub (I'm not sure about the licencing model grub belong to).
I also be very pleased to know which kind of patching do you set in the genuine Stage2 for the xpenology project.
Thanks a lot
4.3 issues
in DSM 5.2 and earlier (Legacy)
Posted
As long we will have the hand on the kernel, we could fool the checks.
My next challenge will be to simulate the ttyS1 serial device and the Uart device check by synobios to avoid any patching.
It will be harder but that's a nice playground
They don't seems to have hardware "protection" stuff as we can found on readynas for example (encryption key in OTP for example).