vulnerabilities-workflow-1.md

Here is the combined list of vulnerabilities, formatted as markdown:

Combined Vulnerability List

This list combines vulnerabilities identified from the provided lists, removing duplicates and formatting them as requested.

• Vulnerability Name: Unchecked Buffer Length in getFileNameByHandle Leading to Out-of-Bounds Read

  • Description: The function getFileNameByHandle (in isatty_windows.go) calls the undocumented NtQueryObject to obtain the full name of a file from its handle. After a successful system call, it uses the first element of a statically allocated buffer (buf[0]) to decide how many UTF‑16 code units to decode from the buffer:

    • A buffer of fixed size ([4 + syscall.MAX_PATH]uint16) is allocated.
    • The function passes this buffer to NtQueryObject without any prior validation of the data that will be populated.
    • Upon success (i.e. if r == 0), it slices the buffer as buf[4 : 4+buf[0]/2] without verifying that buf[0]/2 is less than or equal to len(buf) - 4.

    An attacker who can influence or supply a malicious file handle when the fallback path is used (i.e. when Windows’ GetFileInformationByHandleEx is unavailable) could cause NtQueryObject to return a crafted response. Specifically, by setting buf[0] to an excessively high value, the code will attempt to decode beyond the allocated memory. This can trigger an out-of-bounds read.

  • Impact: Exploiting this vulnerability could lead to one or more of the following:

    • A runtime panic or crash of the application (denial of service).
    • Potential leakage of sensitive memory content adjacent to the statically allocated buffer.
    • In worst-case scenarios, a crafted attack might even allow further exploitation (although Go’s memory safety model makes arbitrary code execution less likely, a crash in a public instance may be enough to disrupt service).

  • Vulnerability Rank: High

  • Currently Implemented Mitigations:

    • The code verifies that the NtQueryObject call returns a success code (r == 0) and returns an error otherwise.
    • However, it does not validate that the length value extracted from buf[0] is within the safe bounds of the allocated buffer.

  • Missing Mitigations:

    • A bounds check for the length field (buf[0]) after the system call: the value should be verified to ensure that buf[0]/2 does not exceed len(buf) - 4.
    • Alternatively, a dynamic buffer allocation or a loop that first queries the required length and then allocates an appropriately sized buffer.
    • Logging or safe error handling for anomalously high length values that could indicate a malicious response.

  • Preconditions:

    • Operating System: The vulnerability is confined to Windows environments.
    • API Fallback Triggered: The fallback code path will be taken when the call to GetFileInformationByHandleEx is not available (i.e. when procGetFileInformationByHandleEx is set to nil during initialization).
    • Attacker Influence on File Handle: The application (or a library that uses this package) must use the function with a file handle that is, directly or indirectly, controllable or influenceable by an external attacker (for example, in a misconfigured or overly permissive context where file descriptors are derived from untrusted sources).

  • Source Code Analysis:

    • In isatty_windows.go, the function getFileNameByHandle is defined as follows:
      • A buffer is allocated: var buf [4 + syscall.MAX_PATH]uint16
      • The call to NtQueryObject is made with the buffer and its byte size:

        r, _, e := syscall.Syscall6(procNtQueryObject.Addr(), 5,
            fd, objectNameInfo, uintptr(unsafe.Pointer(&buf)),
            uintptr(2*len(buf)), uintptr(unsafe.Pointer(&result)), 0)

      • The function then checks if r != 0 and returns an error; however, it does not check the value populated in buf[0].
      • The length used for decoding the file name is calculated as buf[0]/2 and the code slices the buffer as:

        return string(utf16.Decode(buf[4 : 4+buf[0]/2])), nil

      • Risk Point: There is no safeguard to ensure that (4 + buf[0]/2) is within the bounds of the allocated buf array. If an attacker is able to force a malicious response that sets buf[0] to a value exceeding the safe maximum, this slice operation will read memory beyond the allocated area.

  • Security Test Case:

    • Objective: Reproduce the condition where buf[0] holds a maliciously large value, causing the buffer slice to exceed its bounds.

    • Steps:

      1. Test Environment Setup: Create a Windows test environment where you can simulate the behavior of the NtQueryObject call. This could involve stubbing or monkey-patching (or using dependency injection) for procNtQueryObject so that its call returns a successful result (r == 0).
      2. Simulated Malicious Response: Configure the stubbed NtQueryObject call to write into the provided buffer:
         • Set the first element buf[0] to a value that is larger than (len(buf)-4)*2. For instance, if len(buf) is 4 + syscall.MAX_PATH, choose buf[0] so that buf[0]/2 > (len(buf) - 4).
      3. Trigger the Vulnerability: Call the function IsCygwinTerminal(fd) (which under the fallback path will call getFileNameByHandle) using a dummy file handle. Ensure that procGetFileInformationByHandleEx is nil to force the fallback.
      4. Observation: Monitor the application for a crash, runtime panic, or any unexpected behavior that indicates an out-of-bounds read occurred.
      5. Verification: Confirm that with proper bounds checking in place, such an input should be handled safely (for example, by returning an error), thereby confirming the need for the additional mitigations.
      6. Logging: Record all test outputs and error messages to verify that the vulnerability is reproducible.

    • Expected Result: The test should demonstrate that without proper validation, a maliciously large length value leads to an out-of-bounds memory access, resulting in a crash or potential leakage of adjacent memory.