cve-2025-60709 pushed

Author: ghostbyt3

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@@ -284,6 +284,16 @@ The function will create `JUSTASTRINGDnewfile.dll` file but once the validation
 
 **Step 5:** Once we have written a DLL in `C:\Windows\System32\`, then we can directly change the content of the DLL, so if a privileged service load this DLL we can escalate the privilege.
 
+## Patch Analysis
+
+Analysing the patched `HsmpOpCreatePlaceholders()` function, instead of directly calling `IoAllocateMdl()` to allocate a memory descriptor list, it allocates a `POOL_FLAG_PAGED` pool called as `Pool2` (also saved as `Src`) and then copies the data to that pool (Line 123). The old code path is still there for backward compatibility (Line 126).
+
+![image.png](/img/cve-2025-55680/image%205.png)
+
+Now all the user input values are retrieved directly from the newly allocated kernel memory (`Src`).
+
+![image.png](/img/cve-2025-55680/image%206.png)
+
 **References:**
 
 - https://ssd-disclosure.com/cloud-filter-arbitrary-file-creation-eop-patch-bypass-lpe/  

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@@ -0,0 +1,60 @@
+---
+title: "CVE-2025-60709 - Windows Common Log File System Driver Elevation of Privilege Vulnerability"
+pubDate: 2025-12-05
+author: "Ghostbyt3"
+tags: ["1day", "clfs.sys", "windows", "kernel"]
+description: "A vulnerability in the Windows Common Log File System (CLFS) driver allows out-of-bounds memory reads due to insufficient bounds checking in ClfsGetFirstRecord(). The function validates that attacker-controlled record offsets don't exceed `buffer_size + 40` instead of `buffer_size`, enabling reads of up to 40 bytes beyond allocated buffers, potentially leaking sensitive kernel memory for information disclosure or exploit chain development."
+---
+
+A vulnerability in the Windows Common Log File System (CLFS) driver allows out-of-bounds memory reads due to insufficient bounds checking in `ClfsGetFirstRecord()`. The function validates that attacker-controlled record offsets don't exceed `buffer_size + 40` instead of `buffer_size`, enabling reads of up to 40 bytes beyond allocated buffers, potentially leaking sensitive kernel memory for information disclosure or exploit chain development.
+
+**CVE-2025-60709:** https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-60709  
+**Vulnerability Type:** Out-of-bounds Read  
+**Driver Version:** clfs.sys - 10.0.26100.7019  
+
+## Vulnerability analysis
+
+From the patch diffing results, it was found that the ClfsGetFirstRecord() function has significant changes, whereas the other functions have only minor changes.
+
+![image.png](/img/cve-2025-55680/image%203.png)
+
+The vulnerable function is `ClfsGetFirstRecord()`, and as the name suggests, it retrieves the first record of a CLFS log block. Here, `a1` points to a `CLFS_LOG_BLOCK_HEADER` structure, and `a2` is the buffer size.
+
+- **Line 8** – It loads the value at `a1 + 0x28`, which corresponds to the first entry of the `RecordOffsets` array, into `v2`. Therefore, `v2 = RecordOffsets[0]` and represents the offset of the first record.
+- **Line 11** – It obtains the pointer to the first record by computing `a1 + v2` (`a1[v2]`). This value is stored in `result`, which the function will return.
+- The problem lies in the bounds validation.
+- **Line 9** – It checks that the first offset (`RecordOffsets[0]`) does not exceed `0xFFFFFFD8`, which is just a large sanity limit.
+- **Line 12** – This is where the actual issue appears. Instead of properly checking that the offset stays within the buffer, the function only fails when `RecordOffsets[0] > buffer_size + 40`.
+- As a result, the function incorrectly accepts offsets in the range **from `buffer_size` (a2) up to `buffer_size + 0x28` (40 bytes)**. Any value in this range produces an out‑of‑bounds pointer, leading to an out‑of‑bounds read.
+
+![image.png](/img/cve-2025-55680/image.png)
+
+```c++
+typedef struct _CLFS_LOG_BLOCK_HEADER
+{
+    UCHAR MajorVersion;
+    UCHAR MinorVersion;
+    UCHAR Usn;
+    CLFS_CLIENT_ID ClientId;
+    USHORT TotalSectorCount;
+    USHORT ValidSectorCount;
+    ULONG Padding;
+    ULONG Checksum;
+    ULONG Flags;
+    CLFS_LSN CurrentLsn;
+    CLFS_LSN NextLsn;
+    ULONG RecordOffsets[16];
+    ULONG SignaturesOffset;
+} CLFS_LOG_BLOCK_HEADER, *PCLFS_LOG_BLOCK_HEADER;
+```
+
+In order to exploit this vulnerability, the Base Log File must set `RecordOffsets[0]` to an offset that is larger than the buffer size but not larger than `buffer_size + 0x28`.  To reach this vulnerable function, the shortest path is via `CClfsLogFcbPhysical::AppendRegion()` function.
+
+![image.png](/img/cve-2025-55680/image%201.png)
+
+## Patch Analysis
+
+In the patched version, the function first loads `RecordOffsets[0]` into `v4`. It then computes `v5 = v4 + 40` (i.e., `RecordOffsets[0] + 0x28`). In the new bounds check (line 17), it ensures that `RecordOffsets[0] + 40` does not exceed the `buffer size (a2/v2 + 40)`. This patch fixes the original bug by ensuring that `RecordOffsets[0] + 0x28` must not exceed the buffer size, preventing the out‑of‑bounds read.
+
+![image.png](/img/cve-2025-55680/image%202.png)
+