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An origin validation error (CWE-346) affects Synology Assistant versions prior to 7.0.6-50085 on the Windows platform. The vulnerability resides in the application’s component responsible for handling file writes during software installation. Specifically, during the installation process, the Assistant fails to properly validate the origin or source of certain instructions that attempt to write files to the host system. A local attacker can exploit this flaw to write arbitrary files with restricted content, meaning the attacker can control the file path but the content that can be written is limited or restricted in nature. This scenario typically arises when an attacker can intercept or manipulate local installation data or communications to insert a malicious file-writing operation. The vulnerability requires low attack complexity and no special privileges, but user interaction is necessary, as the attack must be triggered during an installation session, and the attacker must already have local access to the machine. This local requirement means the vulnerability cannot be exploited remotely over a network, limiting its risk in isolated environments. However, if an attacker has gained local foothold, they can exploit this flaw to write restricted content to arbitrary locations, which can be chained with other techniques to affect system integrity or availability.
DailyCVE Form:
Platform: Windows only
Version: Before 7.0.6-50085
Vulnerability: Restricted file write
Severity: Medium (CVSS 6.1)
date: 2025-12-08 (advisory)
Prediction: Already patched (2025-08-11)
What Undercode Say:
Check current Synology Assistant version: Navigate to the installation directory (default: C:\Program Files\Synology\SynologyAssistant) Run the following in PowerShell to query the executable version: (Get-Command "C:\Program Files\Synology\SynologyAssistant\Assistant.exe").FileVersionInfo.FileVersion Alternatively, use the Windows Registry: Get-ItemProperty "HKLM:\Software\Synology\Assistant" | Select-Object -ExpandProperty Version To test for vulnerability (requires local access and installation routine): This is a conceptual simulation of the flawed origin validation: 1. Start a new Synology Assistant installation. 2. Intercept local write calls using API monitoring tools like Process Monitor. 3. Craft a custom payload that requests writing a file outside the allowed installation path. Example of a vulnerable function call pattern (hypothetical C++ pseudo-code): WriteFile(hTargetDirectory + "\install.conf", lpBuffer, nNumberOfBytesToWrite, ...); The validation routine does not check if the resolved path stays within the intended sandbox.
How Exploit:
Exploitation requires local access and user interaction, such as initiating a software installation. An attacker with local access would:
1. Launch the Synology Assistant installer.
2. Monitor or intercept the file-writing routines.
- Substitute a malicious file path, such as
C:\Windows\System32\drivers\etc\hosts. - Due to the origin validation error, the restricted content (e.g., a few bytes of text or configuration data) would be written to the chosen location.
- This could lead to denial of service (if critical system files are overwritten) or integrity compromise (if configuration files are altered). No known public exploit code exists for this vulnerability.
Protection:
- Upgrade: Immediately update Synology Assistant to version 7.0.6-50085 or later. The fixed version was released on 2025-08-11.
- Principle of Least Privilege: Run installations and sensitive applications with standard user accounts; avoid using an account with local administrator privileges.
- Application Control: Use Windows AppLocker or similar to block execution of Synology Assistant from untrusted directories.
- Network Isolation: Limit local system access to trusted users; ensure no malicious local processes can interact with the installer.
Impact:
Successful exploitation allows a local attacker with low privileges to write restricted content to arbitrary file paths during an installation session. The primary impacts are:
– Integrity (Low): The attacker can modify configuration or data files with limited content.
– Availability (High): Overwriting critical system files (e.g., drivers, boot configurations) can lead to system crashes or denial of service.
– No Confidentiality Impact: The vulnerability does not allow reading or exfiltrating data.
– No Direct Privilege Escalation: The attacker does not automatically gain higher system privileges; however, the file write can be used as a stepping stone in a multi-stage attack to achieve escalation.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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