text
stringlengths
4
429
imp_level
reliable_n_tries
reliable_keepalive
reliable_rtt
reliable_padding
reliable_no_keepalive
m2b_raw
psk
key
Once the incoming data is authenticated and decrypted, the driver passes it to the DLL by using memory pipes.
For example, on HTTP traffic arrival it may send traffic data into a memory pipe \Device\NamedPipe\isapi_http, and then,
send a received peer-2-peer command message write_peer_nfo=[IP_ADDRESS:PORT]0frag_no_scrambling=Y0 into
another memory pipe called \Device\NamedPipe\isapi_dg.
In order to log its activity, the driver writes log data into the pipe \Device\NamedPipe\isapi_log, so that the DLL could log the
data into the log files.
Full list of the named pipes used for communications is provided below:
\Device\NamedPipe\isapi_http
\Device\NamedPipe\isapi_log
\Device\NamedPipe\isapi_dg
\Device\NamedPipe\services_control
Messages submitted into the pipes are wrapped into the structures. The structures appear to contain headers to allow the pipe
server, that runs within an infected userland module, to identify the messages first and then unwrap the structures accordingly.
For example, the message headers could be:
domc.np
frag.np
Once received from the pipes and unwrapped/decoded, the data is then handled by the usermode DLL as per the data intention -
whether it
s a traffic sniffing task, a peer-2-peer client logic, a logging task, or a task of saving received files into the virtual volumes.
BAE Systems Applied Intelligence: Snake Rootkit Report 2014 19
VIRTUAL FILE VOLUMES
The driver creates virtual file volumes for encrypted storage of its files and configuration data:
\\.\Hd1
\\.\Hd2
The volumes are mounted from the virtual file systems RawDisk1 and RawDisk2.
The first partition is created with the following steps:
the driver creates a 100Mb (0x6400000 bytes) file %windows%\$NtUninstallQ817473$\hotfix.dat by calling
IoCreateFile() API
then it creates a section object with the flags SEC_COMMIT and SEC_NOCACHE (0x18000000) by calling
ZwCreateSection(); the flags mean the file is mapped into memory, the entire range of pages will be committed
next, it maps a view of the created section into the virtual address space by calling ZwMapViewOfSection()
finally, it creates device \Device\RawDisk1 from the section map and mounts it as \\.\Hd1
The hook installed by the rootkit on IofCallDriver() API provides on-the-fly data encryption/decryption whenever that data is
written to or read from the volume. The encryption algorithm is based on CAST-128, with the hard-coded key stored in the rootkit
body.
As a result, whenever the data is saved into the volume Hd1, it will be scrambled on-the-fly, and reflected in the persistent storage
file hotfix.dat, which is physically located within the rootkit
home
directory:
Z:\WINDOWS\$NtuninstallQ817473$>dir
Volume in drive Z has no label.
Volume Serial Number is 2479-98AC
Directory of Z:\WINDOWS\$NtuninstallQ817473$
13/02/2014 04:47 PM <DIR> .
13/02/2014 04:47 PM <DIR> ..
03/02/2014 01:57 PM 210,944 fdisk.sys
13/02/2014 04:47 PM 104,857,600 hotfix.dat
2 File(s) 105,068,544 bytes
2 Dir(s) 8,406,433,792 bytes free
Analysis of the hotfix.dat file contents reveals it
s a fully encrypted file with flat entropy. Thus, it is not possible to reveal the
contents of the Snake
s volume by accessing the contents of this file (unless the encryption is broken, that is).
Enlisting the contents of the created volume is possible, along with creating files on it:
C:\>echo Test > \\.\Hd1\Test.txt
C:\>type \\.\Hd1\\Test.txt
Test
C:\>dir \\.\Hd1\\
Volume in drive \\.\Hd1 has no label.
Volume Serial Number is BA9B-99E8
Directory of \\.\Hd1
14/02/2014 02:22 PM 7 Test.txt
1 File(s) 7 bytes
0 Dir(s) 0 bytes free
BAE Systems Applied Intelligence: Snake Rootkit Report 2014 20
However, as soon as IofCallDriver() hook is removed, the same
command will fail, as with no hook the rootkit cannot
decrypt the scrambled volume:
C:\>dir \\.\Hd1\\
Incorrect function.