基本信息
Windows Cloud Files Mini Filter 驱动中存在越界写入漏洞,在解析Reparse point数据时,由于memcpy函数的长度参数用户可控,源内存可控,导致攻击者可以构造恶意结构并传递给Windows Cloud Files Mini Filter 驱动,造成越界写入,并在内核执行任意代码。
其他
文章发表于:
https://www.ch35tnut.site/zh-cn/vulnerability/cve-2023-36036-windows-cloud-files-mini-filter-driver-eop/
影响版本
略
环境搭建
-
Windows 10 21H2 23年10月补丁
技术分析&调试
cldflt.sys驱动中实现了云文件的各项功能,diff该驱动,修改函数如下:
在HsmpRpiDecompressBuffer
函数中有如下修改,对*(_WORD *)(a1 + 10)
添加了一个判断,是否>0x4000
,
如果大于则抛出错误 0xC000CF02
对应 STATUS_CLOUD_FILE_METADATA_CORRUPT
https://endodermis59.rssing.com/chan-36587470/all_p6.html
AI输出
HsmpRpiDecompressBuffer函数的作用是解压压缩后的Reparse Point数据。
主要功能包括:
1. 校验传入数据的完整性和魔数是否正确
2. 如果数据被压缩,则根据原长度分配解压缓冲区
3. 调用RtlDecompressBuffer进行实际解压
4. 检查解压后数据长度是否匹配
5. 如果解压成功,返回解压后的数据
6. 否则返回错误码
所以它是一个典型的压缩数据解压函数,接收原始压缩数据,校验->分配缓冲区->解压->返回解压后数据的过程。
通过解压让后续代码可以处理未压缩的Reparse Point数据,一般在需要提交/更新数据时会解压。
主要作用就是将压缩后的Reparse Point还原为可读的未压缩数据。
HsmpRpiDecompressBuffer
由 HsmpRpReadBuffer
调用
__int64 __fastcall HsmpRpReadBuffer(PFLT_INSTANCE Instance, PFILE_OBJECT FileObject, unsigned __int16 **a3)
{
...
*a3 = 0i64;
v6 = 1024;
OutputBuffer = (unsigned __int16 *)ExAllocatePoolWithTag(PagedPool, 0x400ui64, 0x70527348u);
v8 = OutputBuffer;
......
}
LODWORD(v9) = HsmpRpiDecompressBuffer((__int64)v8, v6, a3);
HsmDbgBreakOnStatus((unsigned int)v9);
if ( (int)v9 < 0 )
{
v16 = WPP_GLOBAL_Control;
if ( WPP_GLOBAL_Control == (PDEVICE_OBJECT)&WPP_GLOBAL_Control
|| (HIDWORD(WPP_GLOBAL_Control->Timer) & 1) == 0
|| BYTE1(WPP_GLOBAL_Control->Timer) < 2u )
{
goto LABEL_8;
}
v17 = 20i64;
goto LABEL_30;
}
if ( *a3 != v8 )
LABEL_8:
ExFreePoolWithTag(v8, 0x70527348u);
return (unsigned int)v9;
}
AI解释
这段代码实现了解析和解压Reparse Point数据的功能:
1. 分配OutputBuffer内存用于读取Reparse数据。
2. 调用FltFsControlFile读取Reparse数据到OutputBuffer。
3. 如果读取失败,并且错误码表示buffer太小,则重新分配更大的buffer并重试读取。
4. 调用HsmpRpiDecompressBuffer对读取到的数据进行解压。
5. 如果解压成功,返回解压后的数据,否则返回错误码。
6. 释放原始数据内存。
7. 其中包含了详细的错误和日志记录逻辑。
所以总的来说,这段代码用于从文件系统读取Reparse Point数据,然后对数据进行解压和解析,最后返回解析后的数据。
主要功能聚焦在读取压缩数据并解压这块。
HsmpRpReadBuffer
由 HsmpRpCommitNoLock
和 HsmpSetupContexts
调用。
HsmpRpCommitNoLock
解释如下
这个C函数实现了HsmpRpCommitNoLock,它似乎是用于在没有锁的情况下提交页面重播(Page Replay)数据。
主要的逻辑如下:
1. 校验和准备输入数据
2. 分配内存池来存储提交的数据
3. 构建数据结构,填充各种元数据
4. 尝试压缩数据
5. 将数据写入文件
6. 清理临时数据结构和内存
具体来说,这个函数做了以下工作:
1. 验证输入参数的有效性
2. 为输出缓冲区分配内存
3. 构建输出缓冲区的数据结构
4. 填充输出缓冲区的头部
5. 将输入缓冲区的数据复制到输出缓冲区
6. 计算校验和
7. 尝试压缩输出缓冲区
8. 标记文件属性
9. 将输出缓冲区的数据写入文件
10. 重置文件属性
11. 释放临时缓冲区和内存
所以总的来说,这个函数的主要目的是准备并提交页面重播数据,同时处理必要的校验、压缩和清理工作。
在 HsmpRpCommitNoLock
中有如下代码,可以看到在前面diff中出现的0x4000和0x3FFC,可以猜测漏洞产生于该函数中
LABEL_156:
PoolWithTag = (unsigned int *)ExAllocatePoolWithTag(PagedPool, 0x4000ui64, 0x70527348u);
v142 = PoolWithTag;
v11 = (char *)PoolWithTag;
if ( PoolWithTag )
{
0, 0x4000ui64);
v57 = InputBuffer;
v58 = v11 + 4;
if ( v8 && *((_WORD *)v8 + 7) > 0xAu )
v57 = *((_WORD *)v8 + 7);
v59 = (unsigned int *)(v58 + 8);
*)v58 + 6) = 0;
v9 = (unsigned __int64)(v58 + 16);
*)v58 + 7) = v57;
*)v58 + 2) = 8 * v57 + 16;
*)v58 = 'pReF';
+ 16, 0, 8i64 * v57);
if ( *((_WORD *)v58 + 7) )
{
v60 = *v59;
if ( ((v60 + 3) & 0xFFFFFFFFFFFFFFFCui64) + 1 <= 0x3FFC )// 12 偏移
{
(v60 + 3) & 0xFFFFFFFC; =
if ( *(_WORD *)v9 )
*)v58 + 6) |= 1u;
*)v9 = 7;
0; =
*)v58 + 9) = 1;
v61 = *v59;
*)v58 + 5) = v61;
1; =
继续审查代码,发现在HsmpRpCommitNoLock
中有如下代码,在do while循环中调用memmove函数时,传入的src来源于 HsmpRpReadBuffer
解压后的element[10]
数据,dst为ExAllocatePoolWithTag
分配的大小为0x4000的内存。长度参数来源于ElementInfos[10].Length
,不难看出由此可以造成越界写入,且用户可控。
v32 = 0i64;
if ( (v9 & 0x80000000) == 0i64 )
{
v8 = (char *)P + 12;
...
{
if ( (_DWORD)v54 && (_WORD)v55 )
v167 = &v8[v54];
else
v167 = v32;
.....
PoolWithTag = (unsigned int *)ExAllocatePoolWithTag(PagedPool, 0x4000ui64, 0x70527348u);
v142 = PoolWithTag;
v11 = (char *)PoolWithTag;
if ( PoolWithTag )
{
0, 0x4000ui64);
v57 = InputBuffer;
v58 = v11 + 4;
if ( v8 && *((_WORD *)v8 + 7) > 0xAu )
v57 = *((_WORD *)v8 + 7);
v59 = (unsigned int *)(v58 + 8);
*)v58 + 6) = 0;
v9 = (unsigned __int64)(v58 + 16);
*)v58 + 7) = v57;
*)v58 + 2) = 8 * v57 + 16;
*)v58 = 'pReF';
+ 16, 0, 8i64 * v57);
.....
}
+= v109;
.....
if ( *((_WORD *)v58 + 28) )
*)v58 + 6) |= 1u;
(v113 + 3) & 0xFFFFFFFC; =
....
+= v114;
.....
v117 = (char *)v167;
v107 = (char *)Src;
(v118 + 3) & 0xFFFFFFFC; =
*)v58 + 32) = 17;
*)v58 + 33) = v119;
v121 = *v59;
*)v58 + 17) = v121;
if ( &v58[v121] != v117 )
{
v117, v120);
......
v125 = 10;
do
{
v126 = v125;
*)&v58[8 * v125 + 16] = v124->ElementInfos[v125];
(char *)v124 + v124->ElementInfos[v125].Offset, v124->ElementInfos[v125].Length);
++v125;
*)&v58[8 * v126 + 20] = *v59;
+= *(unsigned __int16 *)&v58[8 * v126 + 18];
}
while ( v125 < v124->NumberOfElements );
...
if ( v14 )
0x70527348u);
if ( v11 )
0x70527348u);
return (unsigned int)v9;
}
搜索Reparse point RtlCompressBuffer
,找到文章(https://ipvb.gitee.io/windows/2020/04/24/RealPath/),根据文章 _REPARSE_DATA_BUFFER
定义如下,可以知道传入 HsmpRpiDecompressBuffer
的是 REPARSE_DATA_BUFFER
,其中 ReparseTag
为IO_REPARSE_TAG_CLOUD_3
值 0x9000301A
并且在结构体 HsmReparseBufferRaw
的RawData
成员中存储了由RtlCompressBuffer
压缩的数据HsmReparseBufferRaw
// Handled by cldflt.sys!HsmpRpReadBuffer
struct {
USHORT Flags; // Flags (0x8000 = not compressed)
USHORT Length; // Length of the data (uncompressed)
BYTE RawData[1]; // To be RtlDecompressBuffer-ed
} HsmReparseBufferRaw;
_REPARSE_DATA_BUFFER
定义
typedef struct _REPARSE_DATA_BUFFER {
ULONG ReparseTag; // Reparse tag type
USHORT ReparseDataLength; // Length of the reparse data
USHORT Reserved; // Used internally by NTFS to store remaining length
union {
// Structure for IO_REPARSE_TAG_SYMLINK
// Handled by nt!IoCompleteRequest
struct {
USHORT SubstituteNameOffset;
USHORT SubstituteNameLength;
USHORT PrintNameOffset;
USHORT PrintNameLength;
ULONG Flags;
WCHAR PathBuffer[1];
/* Example of distinction between substitute and print names:
// mklink /d ldrive c:
// SubstituteName: c:\??
// PrintName: c:
*/
} SymbolicLinkReparseBuffer;
// Structure for IO_REPARSE_TAG_MOUNT_POINT
// Handled by nt!IoCompleteRequest
struct {
USHORT SubstituteNameOffset;
USHORT SubstituteNameLength;
USHORT PrintNameOffset;
USHORT PrintNameLength;
WCHAR PathBuffer[1];
} MountPointReparseBuffer;
// Structure for IO_REPARSE_TAG_WIM
// Handled by wimmount!FPOpenReparseTarget->wimserv.dll
// (wimsrv!ImageExtract)
struct {
GUID ImageGuid; // GUID of the mounted VIM image
BYTE ImagePathHash[0x14]; // Hash of the path to the file within the
// image
} WimImageReparseBuffer;
// Structure for IO_REPARSE_TAG_WOF
// Handled by FSCTL_GET_EXTERNAL_BACKING, FSCTL_SET_EXTERNAL_BACKING in
// NTFS (Windows 10+)
struct {
//-- WOF_EXTERNAL_INFO --------------------
ULONG Wof_Version; // Should be 1 (WOF_CURRENT_VERSION)
ULONG Wof_Provider; // Should be 2 (WOF_PROVIDER_FILE)
//-- FILE_PROVIDER_EXTERNAL_INFO_V1 --------------------
ULONG FileInfo_Version; // Should be 1 (FILE_PROVIDER_CURRENT_VERSION)
ULONG
FileInfo_Algorithm; // Usually 0 (FILE_PROVIDER_COMPRESSION_XPRESS4K)
} WofReparseBuffer;
// Structure for IO_REPARSE_TAG_APPEXECLINK
struct {
ULONG StringCount; // Number of the strings in the StringList, separated
// by ''
WCHAR StringList[1]; // Multistring (strings separated by '',
// terminated by '')
} AppExecLinkReparseBuffer;
// Structure for IO_REPARSE_TAG_WCI (0x80000018)
struct {
ULONG Version; // Expected to be 1 by wcifs.sys
ULONG Reserved;
GUID LookupGuid; // GUID used for lookup in wcifs!WcLookupLayer
USHORT WciNameLength; // Length of the WCI subname, in bytes
WCHAR WciName[1]; // The WCI subname (not zero terminated)
} WcifsReparseBuffer;
// Handled by cldflt.sys!HsmpRpReadBuffer
struct {
USHORT Flags; // Flags (0x8000 = not compressed)
USHORT Length; // Length of the data (uncompressed)
BYTE RawData[1]; // To be RtlDecompressBuffer-ed
} HsmReparseBufferRaw;
// Dummy structure
struct {
UCHAR DataBuffer[1];
} GenericReparseBuffer;
} DUMMYUNIONNAME;
} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;
在这个Github仓库(https://github.com/ladislav-zezula/FileTest)中实现了对Reparse point的解析,其中定义了HSM_REPARSE_DATA
typedef struct _HSM_ELEMENT_INFO
{
USHORT Type; // Type of the element (?). One of HSM_ELEMENT_TYPE_XXX
USHORT Length; // Length of the element data in bytes
ULONG Offset; // Offset of the element data, relative to begin of HSM_DATA. Aligned to 4 bytes
} HSM_ELEMENT_INFO, *PHSM_ELEMENT_INFO;
typedef struct _HSM_DATA
{
ULONG Magic; // 0x70527442 ('pRtB') for bitmap data, 0x70526546 ('FeRp') for file data
ULONG Crc32; // CRC32 of the following data (calculated by RtlComputeCrc32)
ULONG Length; // Length of the entire HSM_DATA in bytes
USHORT Flags; // HSM_DATA_XXXX
USHORT NumberOfElements; // Number of elements
HSM_ELEMENT_INFO ElementInfos[1]; // Array of element infos. There is fixed maximal items for bitmap and reparse data
} HSM_DATA, *PHSM_DATA;
typedef struct _HSM_REPARSE_DATA
{
USHORT Flags; // Lower 8 bits is revision (must be 1 as of Windows 10 16299)
// Flags: 0x8000 = Data needs to be decompressed by RtlCompressBuffer
USHORT Length; // Length of the HSM_REPARSE_DATA structure (including "Flags" and "Length")
HSM_DATA FileData; // HSM data
} HSM_REPARSE_DATA, *PHSM_REPARSE_DATA;
对应在 REPARSE_DATA_BUFFER
的偏移如下
0:000> dt pa
Local var @ 0xa8444fec08 Type _REPARSE_DATA_BUFFER*
0x000001e0`ef867690
+0x000 ReparseTag : 0x9000301a
+0x004 ReparseDataLength : 0x
+0x006 Reserved : 0
+0x008 SymbolicLinkReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-SymbolicLinkReparseBuffer>
+0x008 MountPointReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-MountPointReparseBuffer>
+0x008 WimImageReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-WimImageReparseBuffer>
+0x008 WofReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-WofReparseBuffer>
+0x008 AppExecLinkReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-AppExecLinkReparseBuffer>
+0x008 WcifsReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-WcifsReparseBuffer>
+0x008 hsm_reparse_data : _HSM_REPARSE_DATA
+0x008 GenericReparseBuffer : _REPARSE_DATA_BUFFER::<unnamed-tag>::<unnamed-type-GenericReparseBuffer>
0:000> dx -r1 (*((poc3!_HSM_REPARSE_DATA *)0x1e0ef867698))
(*((poc3!_HSM_REPARSE_DATA *)0x1e0ef867698)) [Type: _HSM_REPARSE_DATA]
[+0x000] Flags : 0x [Type: unsigned short] // 8
[+0x002] Length : 0x [Type: unsigned short] // 10
[+0x004] FileData [Type: _HSM_DATA] // 12
0:000> dx -r1 (*((poc3!_HSM_DATA *)0x1e0ef86769c))
(*((poc3!_HSM_DATA *)0x1e0ef86769c)) [Type: _HSM_DATA]
[+0x000] Magic : 0x70526546 [Type: unsigned long] // 12
[+0x004] Crc32 : 0x31e13b17 [Type: unsigned long] // 16
[+0x008] Length : 0x [Type: unsigned long] // 20
[+0x00c] Flags : 0x2 [Type: unsigned short] // 24
[+0x00e] NumberOfElements : 0x [Type: unsigned short] // 26
[+0x010] ElementInfos [Type: _HSM_ELEMENT_INFO [10) // 28
PoC构造
将结构体导入到ida中,在HsmpRpCommitNoLock
中首先对ReparseTag进行验证,而后将hsm_reparse_data和对应的长度导入到 HsmpRpValidateBuffer
函数中验证。
if ( (reparse_data_buffer->ReparseTag & 0xFFFF0FFF) != dword_1C00235D0 )
{
LODWORD(v9) = -1073688821;
HsmDbgBreakOnStatus(3221278475i64);
if ( WPP_GLOBAL_Control != (PDEVICE_OBJECT)&WPP_GLOBAL_Control
&& (HIDWORD(WPP_GLOBAL_Control->Timer) & 1) != 0
&& BYTE1(WPP_GLOBAL_Control->Timer) >= 2u )
{
WPP_SF_qiqDDd(
WPP_GLOBAL_Control->AttachedDevice,
2i64,
v30,
a2,
*(_QWORD *)(v5 + 32),
v29,
dword_1C00235D0,
reparse_data_buffer->ReparseTag);
}
goto LABEL_8;
}
ReparseDataLength = reparse_data_buffer->ReparseDataLength;
v9 = (unsigned int)HsmpRpValidateBuffer(&reparse_data_buffer->DUMMYUNIONNAME.hsm_reparse_data, ReparseDataLength);
在 HsmpRpValidateBuffer
函数中对HSM_DATA结构体的一些字段做了如下校验。
-
reparse_data_buffer->ReparseDataLength > 4
-
reparse_data_buffer->hsm_reparse_data.Flags=1
-
reparse_data_buffer->hsm_reparse_data.FileData.Magic = ‘pReF’
-
reparse_data_buffer->hsm_reparse_data.FileData.Flags = 2, 并且reparse_data_buffer->hsm_reparse_data.FileData.Crc32 == RtlComputeCrc32(0, (PUCHAR)&a1->FileData.Length, v2 - 8
-
NumberOfElements 不为0,且最大为10,最后一个以NONE结尾
特别的,从如下代码中可以看到对ElementInfos[0]
和ElementInfos[1]
进行了校验,容易得出如下条件:
-
NumberOfElements > 1
-
FileData.Length >= 0x20
-
`FileData.ElementInfos[1].Type == 0xA
-
FileData.ElementInfos[1].Offset >= 8 * NumberOfElements + 16 && FileData.ElementInfos[1].Offset < FileData.Length
-
FileData.ElementInfos[1].Length == 4
-
FileData.ElementInfos[1].Length + FileData.ElementInfos[1].Offset < 65535
if ( (unsigned __int16)NumberOfElements > 1u
&& (unsigned int)Length >= 0x20
&& (v22 = a1->FileData.ElementInfos[1].Type, v22 < 0x12u)
&& ((v23 = a1->FileData.ElementInfos[1].Offset, !(_DWORD)v23) || v23 >= hsm_data_length)
&& (unsigned int)v23 <= (unsigned int)Length
&& (v24 = a1->FileData.ElementInfos[1].Length, v24 <= (unsigned int)Length)
&& v24 + (unsigned int)v23 >= (unsigned int)v23
&& v24 + (unsigned int)v23 <= (unsigned int)Length
&& v22 == 10
&& v24 == 4 )
{
v5 = *(ULONG *)((char *)&p_FileData->Magic + v23);
IsReparseBufferSupported = 0;
}
else
{
IsReparseBufferSupported = 0xC0000225;
}
如下代码对ElementInfos[2]
进行了校验,有如下:
-
FileData.ElementInfos[2].Offset < FileData.Length
-
FileData.ElementInfos[2].Length < FileData.Length
-
FileData.ElementInfos[2].Type == 6
if ( (element_1_Data & 0x10) != 0 )
return IsReparseBufferSupported;
v27 = a1->FileData.Length;
if ( v27 < 0x18
|| (v28 = a1->FileData.NumberOfElements, (unsigned __int16)v28 <= 2u)
|| v27 < 0x28
|| (v29 = a1->FileData.ElementInfos[2].Type, v29 >= 0x12u)
|| (v30 = a1->FileData.ElementInfos[2].Offset, (_DWORD)v30) && v30 < 8 * v28 + 16
|| (unsigned int)v30 > v27
|| (v31 = a1->FileData.ElementInfos[2].Length, v31 > v27)
|| v31 + (unsigned int)v30 < (unsigned int)v30
|| v31 + (unsigned int)v30 > v27
|| v29 != 6
|| (IsReparseBufferSupported = 0, v31 != 8) )
{
IsReparseBufferSupported = 0xC0000225;
}
后面还有一堆校验逻辑就不贴了。
在 HsmpRpCommitNoLock
中对 HsmpRpValidateBuffer
返回值做了校验,如果IsReparseBufferSupported
不为0则会进入报错逻辑.
IsReparseBufferSupported = (unsigned int)HsmpRpValidateBuffer(
&reparse_data_buffer->DUMMYUNIONNAME.hsm_reparse_data,
ReparseDataLength);
HsmDbgBreakOnStatus(IsReparseBufferSupported);
v32 = 0i64;
if ( (IsReparseBufferSupported & 0x80000000) == 0i64 )
{
...
}
else
{
HsmDbgBreakOnCorruption();
if ( a4 == (_BYTE)v32 )
{
if ( WPP_GLOBAL_Control != (PDEVICE_OBJECT)&WPP_GLOBAL_Control
&& (HIDWORD(WPP_GLOBAL_Control->Timer) & 1) != 0
在HsmpRpValidateBuffer
中可以看到当通过第一次校验后,如果ElementInfos[1]
的Data & 0x10 则会直接返回,此时IsReparseBufferSupported=0
能通过校验。
if ( (unsigned __int16)NumberOfElements > 1u
&& (unsigned int)Length >= 0x20
&& (v22 = a1->FileData.ElementInfos[1].Type, v22 < 0x12u)
&& ((v23 = a1->FileData.ElementInfos[1].Offset, !(_DWORD)v23) || v23 >= hsm_data_length)
&& (unsigned int)v23 <= (unsigned int)Length
&& (v24 = a1->FileData.ElementInfos[1].Length, v24 <= (unsigned int)Length)
&& v24 + (unsigned int)v23 >= (unsigned int)v23
&& v24 + (unsigned int)v23 <= (unsigned int)Length
&& v22 == 10
&& v24 == 4 )
{
element_1_Data = *(ULONG *)((char *)&p_FileData->Magic + v23);
IsReparseBufferSupported = 0;
}
else
{
IsReparseBufferSupported = 0xC0000225;
}
HsmDbgBreakOnStatus(IsReparseBufferSupported);
if ( (IsReparseBufferSupported & 0x80000000) != 0 )
{
v25 = WPP_GLOBAL_Control;
if ( WPP_GLOBAL_Control == (PDEVICE_OBJECT)&WPP_GLOBAL_Control
|| (HIDWORD(WPP_GLOBAL_Control->Timer) & 1) == 0
|| BYTE1(WPP_GLOBAL_Control->Timer) < 2u )
{
return IsReparseBufferSupported;
}
v26 = 24i64;
goto LABEL_163;
}
if ( (element_1_Data & 0x10) != 0 )
return IsReparseBufferSupported;
通过构造ElementInfos[0]
和ElementInfos[1]
可以通过HsmpRpValidateBuffer
校验,而后漏洞触发点会读取ElementInfos[10]
的数据和Length通过memcpy进行拷贝,所以还需要构造ElementInfos[10]
的数据,并且ElementInfos[10]
的Length需要超过目标缓冲区,特别的在计算CRC32后,需要通过RtlCompressBuffer压缩目标数据,并放入到FileData处。
构造多大的缓冲区?根据前面补丁分析,在补丁中限制了ReparseDataLength < 0x4000,所以超过四千的部分会造成溢出,如果想溢出8个字节则需要构造0x4008 + 8 = 0x4010,依此类推,在构造缓冲区时。
如何将构造好的数据传递给驱动并在目标位置触发呢?在网上查到有类似漏洞分析文章Windows云文件迷你过滤器驱动程序中的提权漏洞(CVE-2021-31969)(https://zhuanlan.zhihu.com/p/392194464),不难看出CVE-2021-31969修复和本次分析的漏洞CVE-2023-36036修复位置类似,都对ReparseDataLength进行了判断,所以本次PoC编写也可以借鉴。
在CVE-2021-31969分析文章中贴出了部分PoC,结合这部分PoC和前面的结构体,写出PoC也就不难了。
动态调试
在如下两个位置下断点
bp cldflt!HsmpRpCommitNoLock
bp cldflt!HsmpRpCommitNoLock+0x13de
运行poc,可以看到已经进入HsmpRpCommitNoLock
函数
1: kd> g
Breakpoint 0 hit
cldflt!HsmpRpCommitNoLock:
fffff804`6f6a1e88 48895c2420 mov qword ptr [rsp+20h],rbx
继续运行,触发第二个断点
0: kd> g
Breakpoint 1 hit
cldflt!HsmpRpCommitNoLock+0x13de:
fffff804`6f6a3266 e81571faff call cldflt!memcpy (fffff804`6f64a380)
此时memmove已经被优化为memcpy,而要拷贝的长度为0x3f94,dst所在的堆大小为0x4000,dst指向偏移0x74处,最多有0x3f8c大小,所以memcpy拷贝时会越界写入8个字节,造成堆溢出。
1: kd> rr8
r8=0000000000003f94
1: kd> !pool rcx
Pool page ffffd980717f7074 region is Paged pool
large page allocation, tag is HsRp, size is 0x4000 bytes :
Unknown (update pooltag.txt) :
继续运行,则在memcpy内部触发异常,因为尝试往未分配的内存里面写入00
0: kd> u
cldflt!memcpy+0x165:
fffff800`8186a4e5 0f2941f0 movaps xmmword ptr [rcx-10h],xmm0
0: kd> !pool rcx - 0x10
Pool page ffffe5028e4fa000 region is Paged pool
ffffe5028e4fa000 is not a valid large pool allocation, checking large session pool...
ffffe5028e4fa000 is not valid pool. Checking for freed (or corrupt) pool
Address ffffe5028e4fa000 could not be read. It may be a freed, invalid or paged out page
0: kd> rxmm0
xmm0=0000000000000000
对应代码为
if ( v25 )
*(_OWORD *)(v15 + v25 - 16) = *(_OWORD *)(v15 + v25 - 16 + v13);
*(__m128 *)(v15 - 0x10) = v14;
以下为调用栈
1: kd> k
# Child-SP RetAddr Call Site
00 fffffb8a`8a45e4f8 fffff804`63717f82 nt!DbgBreakPointWithStatus
01 fffffb8a`8a45e500 fffff804`63717566 nt!KiBugCheckDebugBreak+0x12
02 fffffb8a`8a45e560 fffff804`635fd747 nt!KeBugCheck2+0x946
03 fffffb8a`8a45ec70 fffff804`63638f6f nt!KeBugCheckEx+0x107
04 fffffb8a`8a45ecb0 fffff804`63430730 nt!MiSystemFault+0x1de5ff
05 fffffb8a`8a45edb0 fffff804`6360d1d8 nt!MmAccessFault+0x400
06 fffffb8a`8a45ef50 fffff804`6f64a4e1 nt!KiPageFault+0x358
07 fffffb8a`8a45f0e8 fffff804`6f6a326b cldflt!memcpy+0x161
08 fffffb8a`8a45f0f0 fffff804`6f6a983b cldflt!HsmpRpCommitNoLock+0x13e3
09 fffffb8a`8a45f230 fffff804`6f66f0d7 cldflt!HsmiOpUpdatePlaceholderDirectory+0x57f
0a fffffb8a`8a45f320 fffff804`6f674b65 cldflt!HsmFltProcessUpdatePlaceholder+0x443
0b fffffb8a`8a45f3d0 fffff804`6f6a4504 cldflt!HsmFltProcessHSMControl+0x3d5
0c fffffb8a`8a45f500 fffff804`647264cc cldflt!HsmFltPreFILE_SYSTEM_CONTROL+0x6a4
0d fffffb8a`8a45f5a0 fffff804`64725f7a FLTMGR!FltpPerformPreCallbacksWorker+0x36c
0e fffffb8a`8a45f6c0 fffff804`64725021 FLTMGR!FltpPassThroughInternal+0xca
0f fffffb8a`8a45f710 fffff804`6475ae2f FLTMGR!FltpPassThrough+0x541
10 fffffb8a`8a45f7a0 fffff804`63410665 FLTMGR!FltpFsControl+0xbf
11 fffffb8a`8a45f800 fffff804`6380142c nt!IofCallDriver+0x55
12 fffffb8a`8a45f840 fffff804`63801081 nt!IopSynchronousServiceTail+0x34c
13 fffffb8a`8a45f8e0 fffff804`638d9ed6 nt!IopXxxControlFile+0xc71
14 fffffb8a`8a45fa20 fffff804`63610ef5 nt!NtFsControlFile+0x56
15 fffffb8a`8a45fa90 00007ff9`c648d704 nt!KiSystemServiceCopyEnd+0x25
16 00000056`01aff5b8 00007ff6`5e59167f ntdll!NtFsControlFile+0x14
17 00000056`01aff5c0 00000000`000001bc 0x00007ff6`5e59167f
18 00000056`01aff5c8 00000000`00000000 0x1bc
PoC会在过几天上传到GitHub
https://github.com/Chestnuts4/POC
小结
本次漏洞分析离不开业内前辈逆向得出的_HSM_REPARSE_DATA结构体信息,这个结构体微软没有公开的文档,相关资料也很少。可以看到早在2018年,就已经逆向出了HSM相关数据结构信息。目前只有这一个仓库有相关信息,向前辈致敬。
/*****************************************************************************/
/* ReparseDataHsm.h Copyright (c) Ladislav Zezula 2018 */
/*---------------------------------------------------------------------------*/
/* Interface of the HSM reparse data structures */
/*---------------------------------------------------------------------------*/
/* Date Ver Who Comment */
/* -------- ---- --- ------- */
/* 06.09.18 1.00 Lad The first version of ReparseDataHsm.h */
/*****************************************************************************/
这里引用一下前辈的主页。
https://www.zezula.net/en/tools/main.html
整体来看,这个漏洞原理和触发方式较为简单,在使用memcpy之前没有校验长度,而修复也简单,再解压之前验证长度是否超过0x4000,超过则认为数据有错,进入到错误逻辑,从而在源头阻止了触发漏洞逻辑。
在漏洞修复处在修复上个整数下溢的漏洞时,开发人员只修复当时的整数下溢漏洞,没有去考虑长度会不会过长,某些程度来说这也是开发的粗心大意导致了这个漏洞留到现在。
在编写PoC参考了其他安全研究员已有的分析。
至于Exploit部分还得再研究一下。
参考链接
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-36036
https://zhuanlan.zhihu.com/p/392194464
https://github.com/microsoft/Windows-classic-samples/tree/main/Samples/CloudMirror
https://learn.microsoft.com/en-us/windows/win32/cfapi/cloud-filter-reference
https://learn.microsoft.com/zh-cn/windows/win32/cfapi/cloud-files-functions
https://learn.microsoft.com/en-us/windows/win32/api/_cloudapi/
原文始发于微信公众号(闲聊趣说):CVE-2023-36036 Windows Cloud Files Mini Filter Driver 权限提升漏洞分析
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