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[原创]虚拟机视角-读写客户机任意内存（win10）
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发表于: 2024-9-26 17:32
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基于windows的内存分页机制，进程间的隔离让我们无法直接读写其他进程的地址空间，又因为copy on write让我们即使patch了系统dll也无法影响其他进程。但是这一根内存条就插在主板上，就不能有个方法能看到内容么？
在裸机上如果没有定制的外设是无解了，但是在虚拟化的框架下，这一切都显得再正常不过。
在虚拟化的框架下，客户机的“内存条”实际上是宿主机上申请的一段普通内存，如果我们能够找到GVA与HVA之间的映射关系，就可以绕开任何限制，直接在宿主机上读写任意位置的客户机内存。
我们先暂停vm后，通过KVM_GET_SREGS即可获取cr3寄存器。
gs寄存器在R0下存放的是KPCR，在R3下存放的是TEB
通过偏移计算KTHREAD->KPROCESS->EPROCESS->active_process_links获得这个进程双链表结构，通过遍历active_process_links我们可以获取当前系统所有进程，包括每个进程的CR3。
关于windows的分页机制，文档很多不赘述直接贴出部分代码
在能够获取所有进程cr3后，加上页表解析，可以轻松的在host上读写任意guest内存。当我们尝试在host抹掉guest进程notepad中的ntdll的PE头后，由于系统dll的特殊性加上直接修改了物理内存，系统也随之陷入一片混乱 
https://github.com/tenclass/mvisor
使用右ctrl+F8唤起debug窗口，目前仅支持win10 guest。
machine_->Pause();
bool success = false;
for (auto vcpu : machine_->vcpus()) {
struct kvm_sregs sregs;
if (ioctl(vcpu->fd(), KVM_GET_SREGS, &sregs) < 0)
MV_PANIC("KVM_GET_REGS failed");
...machine_->Pause();
bool success = false;
for (auto vcpu : machine_->vcpus()) {
struct kvm_sregs sregs;
if (ioctl(vcpu->fd(), KVM_GET_SREGS, &sregs) < 0)
MV_PANIC("KVM_GET_REGS failed");
......if ((sregs.cs.base & 3) != 0) {
MV_LOG("current vcpu=%d is in usermode", vcpu->vcpu_id());
continue;
}auto kpcr = (uint8_t*)GuestVAToHostAddress((uint64_t)sregs.gs.base, sregs.cr3);
......if ((sregs.cs.base & 3) != 0) {
MV_LOG("current vcpu=%d is in usermode", vcpu->vcpu_id());
continue;
}auto kpcr = (uint8_t*)GuestVAToHostAddress((uint64_t)sregs.gs.base, sregs.cr3);
...//0xb080 bytes (sizeof)
struct _KPCR{ union
{
struct _NT_TIB NtTib; //0x0
struct
{
union _KGDTENTRY64* GdtBase; //0x0
struct _KTSS64* TssBase; //0x8
ULONGLONG UserRsp; //0x10
struct _KPCR* Self; //0x18
struct _KPRCB* CurrentPrcb; //0x20
struct _KSPIN_LOCK_QUEUE* LockArray; //0x28
VOID* Used_Self; //0x30
};
};
union _KIDTENTRY64* IdtBase; //0x38
ULONGLONG Unused[2]; //0x40
UCHAR Irql; //0x50
UCHAR SecondLevelCacheAssociativity; //0x51
UCHAR ObsoleteNumber; //0x52
UCHAR Fill0; //0x53
ULONG Unused0[3]; //0x54
USHORT MajorVersion; //0x60
USHORT MinorVersion; //0x62
ULONG StallScaleFactor; //0x64
VOID* Unused1[3]; //0x68
ULONG KernelReserved[15]; //0x80
ULONG SecondLevelCacheSize; //0xbc
ULONG HalReserved[16]; //0xc0
ULONG Unused2; //0x100
VOID* KdVersionBlock; //0x108
VOID* Unused3; //0x110
ULONG PcrAlign1[24]; //0x118
struct _KPRCB Prcb; //0x180
}; //0x700 bytes (sizeof)
struct _KPRCB{ ULONG MxCsr; //0x0
UCHAR LegacyNumber; //0x4
UCHAR ReservedMustBeZero; //0x5
UCHAR InterruptRequest; //0x6
UCHAR IdleHalt; //0x7
struct _KTHREAD* CurrentThread; //0x8
struct _KTHREAD* NextThread; //0x10
struct _KTHREAD* IdleThread; //0x18
UCHAR NestingLevel; //0x20
UCHAR ClockOwner; //0x21
union
{
UCHAR PendingTickFlags; //0x22
struct
{
UCHAR PendingTick:1; //0x22
UCHAR PendingBackupTick:1; //0x22
};
};
UCHAR IdleState; //0x23
ULONG Number; //0x24
ULONGLONG RspBase; //0x28
ULONGLONG PrcbLock; //0x30
CHAR* PriorityState; //0x38
CHAR CpuType; //0x40
CHAR CpuID; //0x41
union
{
USHORT CpuStep; //0x42
struct
{
UCHAR CpuStepping; //0x42
UCHAR CpuModel; //0x43
};
};
ULONG MHz; //0x44
ULONGLONG HalReserved[8]; //0x48
USHORT MinorVersion; //0x88
USHORT MajorVersion; //0x8a
UCHAR BuildType; //0x8c
UCHAR CpuVendor; //0x8d
UCHAR LegacyCoresPerPhysicalProcessor; //0x8e
UCHAR LegacyLogicalProcessorsPerCore; //0x8f
ULONGLONG TscFrequency; //0x90
ULONG CoresPerPhysicalProcessor; //0x98
ULONG LogicalProcessorsPerCore; //0x9c
ULONGLONG PrcbPad04[4]; //0xa0
struct _KNODE* ParentNode; //0xc0
ULONGLONG GroupSetMember; //0xc8
UCHAR Group; //0xd0
UCHAR GroupIndex; //0xd1
UCHAR PrcbPad05[2]; //0xd2
ULONG InitialApicId; //0xd4
ULONG ScbOffset; //0xd8
ULONG ApicMask; //0xdc
VOID* AcpiReserved; //0xe0
ULONG CFlushSize; //0xe8
ULONGLONG PrcbPad11[2]; //0xf0
struct _KPROCESSOR_STATE ProcessorState; //0x100
struct _XSAVE_AREA_HEADER* ExtendedSupervisorState; //0x6c0
ULONG ProcessorSignature; //0x6c8
ULONG ProcessorFlags; //0x6cc
ULONGLONG PrcbPad12a; //0x6d0
ULONGLONG PrcbPad12[3]; //0x6d8
}; //0xb080 bytes (sizeof)
struct _KPCR{ union
{
struct _NT_TIB NtTib; //0x0
struct
{
union _KGDTENTRY64* GdtBase; //0x0
struct _KTSS64* TssBase; //0x8
ULONGLONG UserRsp; //0x10
struct _KPCR* Self; //0x18
struct _KPRCB* CurrentPrcb; //0x20
struct _KSPIN_LOCK_QUEUE* LockArray; //0x28
VOID* Used_Self; //0x30
};
};
union _KIDTENTRY64* IdtBase; //0x38
ULONGLONG Unused[2]; //0x40
UCHAR Irql; //0x50
UCHAR SecondLevelCacheAssociativity; //0x51
UCHAR ObsoleteNumber; //0x52
UCHAR Fill0; //0x53
ULONG Unused0[3]; //0x54
USHORT MajorVersion; //0x60
USHORT MinorVersion; //0x62
ULONG StallScaleFactor; //0x64
VOID* Unused1[3]; //0x68
ULONG KernelReserved[15]; //0x80
ULONG SecondLevelCacheSize; //0xbc
ULONG HalReserved[16]; //0xc0
ULONG Unused2; //0x100
VOID* KdVersionBlock; //0x108
VOID* Unused3; //0x110
ULONG PcrAlign1[24]; //0x118
struct _KPRCB Prcb; //0x180
}; //0x700 bytes (sizeof)
struct _KPRCB{ ULONG MxCsr; //0x0
UCHAR LegacyNumber; //0x4
UCHAR ReservedMustBeZero; //0x5
UCHAR InterruptRequest; //0x6
UCHAR IdleHalt; //0x7
struct _KTHREAD* CurrentThread; //0x8
struct _KTHREAD* NextThread; //0x10
struct _KTHREAD* IdleThread; //0x18
UCHAR NestingLevel; //0x20
UCHAR ClockOwner; //0x21
union
{
UCHAR PendingTickFlags; //0x22
struct
{
UCHAR PendingTick:1; //0x22
UCHAR PendingBackupTick:1; //0x22
};
};
UCHAR IdleState; //0x23
ULONG Number; //0x24
ULONGLONG RspBase; //0x28
ULONGLONG PrcbLock; //0x30
CHAR* PriorityState; //0x38
CHAR CpuType; //0x40
CHAR CpuID; //0x41
union
{
USHORT CpuStep; //0x42
struct
{
UCHAR CpuStepping; //0x42
UCHAR CpuModel; //0x43
};
};
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最后于 2024-9-27 13:39
被Justgoon编辑
，原因：
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kvm提供的接口，用来获取vm寄存器信息的，mvisor/qemu这样的虚拟机都是通过kvm的接口来控制虚拟机 |
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不正确是什么意思？出发page fault了么，guest里面如果缺页目前没有处理，没想到好办法，如果想验证的话可以用processhacker在vm内访问一下那块内存，然后就可以在外面解出来了；也有可能是windows10版本问题，我用的偏移是22h2 19045 |
