Datasets:
clydeiii
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cybersecurity

Dataset card Data Studio Files
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Community
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ZwCreateKey
ZwSaveKey
ZwReadFile
ZwQuerySystemInformation
ZwQueryInformationProcess
ZwClose
ZwTerminateProcess
ZwShutdownSystem
ObOpenObjectByName
BAE Systems Applied Intelligence: Snake Rootkit Report 2014 14
For example, the hook handlers of the registry-related APIs will block access to the registry entries that contain the name of the
driver. In one example, the rootkit blocks access to registry entries that contain the strings
Ultra3
and
~ROOT
The ZwReadFile() hook handler will block access to the home directory where the rootkit keeps its file. In one of the analysed
kernel-centric Snake samples the home directory was hard-coded as %windows%\$NtUninstallQ817473$, so it blocked file
read access from that directory.
The ZwClose() hook handler is used to inject the DLL module into the userland processes.
The hook handler for ZwTerminateProcess() checks if the process being shut down is svchost.exe. If so, it considers
it to be a system shutdown, so it unloads its usermode DLL and deactivates its own network drivers, just like it does when its
ZwShutdownSystem() hook handler gets invoked.
The ObOpenObjectByName() hook is designed to hide the presence of its virtual partitions (described later).
To encrypt data stored on its virtual partitions, the driver sets a hook for another API:
IofCallDriver()
To re-infect the usermode process svchost.exe and to re-enable its network drivers, the rootkit hooks these APIs:
ZwCreateThread
ZwCreateUserProcess
WFP CALLOUT DRIVER
Snake then proceeds to the task of deep packet inspection and modification.
In order to accomplish it, it registers a callout driver for Windows Filtering Platform (WFP), an architecture first introduced with
Windows Vista and nowadays normally used by antivirus and/or intrusion detection systems to inspect/block malicious traffic.
Snake sets filters at the layers FWPM_LAYER_STREAM_V4 and FWPM_LAYER_ALE_FLOW_ESTABLISHED_V4 in the TCP/
IP stack, so that its callout driver is notified whenever a TCP connection is established by a browser. When that happens, the
rootkit triggers an event named \BaseNamedObjects\wininet_activate. When the data arrives, it is intercepted with the
FwpsCopyStreamDataToBuffer0() API, and then scanned for the presence of the hidden commands from C&C.
The driver inspects bidirectional network data on a per stream basis, as it
s located right on the stream data path. An ability to
manipulate data streams is provided with the packet injection logic below, allowing Snake to covertly insert traffic destined to its
C&C servers:
01 int __stdcall stream_inject(int flowHandle, int calloutId, int layerId)
02 {
03 int iRet = 0;
04 int ntStatus = FwpsAllocateNetBufferAndNetBufferList(m_hNdisNblPool, 0, 0, 0, 0, &iRet);
05 if (!ntStatus)
06 {
07 ntStatus = _FwpsStreamInjectAsync(m_hInjection,
08 0,
09 0,
10 flowHandle,
11 calloutId,
12 layerId,
13 20,
14 3,
15 iRet,
16 0,
17 sStreamInjectCompletion,
18 0);
19 if (!ntStatus)
20 {
21 iRet = 0;
22 }
23 if (iRet)
24 {
25 FwpsFreeNetBufferList(iRet);
26 }
27 return ntStatus;
28 }
BAE Systems Applied Intelligence: Snake Rootkit Report 2014 15
In order to qualify as a browser, the usermode process must have any of the following names:
01 bool isBrowserProcess(const wchar_t *szProcName)
02 {
03 return !wcsicmp(szProcName, L
iexplore.exe
) ||
04 !wcsicmp(szProcName, L
firefox.exe
) ||
05 !wcsicmp(szProcName, L
opera.exe
) ||
06 !wcsicmp(szProcName, L
netscape.exe
) ||
07 !wcsicmp(szProcName, L
mozilla.exe
) ||
08 !wcsicmp(szProcName, L
chrome.exe