CVE-2025-1683 Overview
CVE-2025-1683 is a symbolic link following vulnerability [CWE-59] in the Nomad module of the 1E Client on Windows. Versions prior to 25.3 fail to properly resolve links before file access. A local unprivileged attacker can exploit this flaw to delete arbitrary files on the host. The deletion occurs in the context of the privileged 1E Client service, allowing an attacker to remove files they would otherwise lack permission to modify. This primitive can be chained with other techniques to achieve privilege escalation on affected Windows endpoints.
Critical Impact
A local low-privileged user can leverage symbolic link manipulation to delete arbitrary files protected by SYSTEM-level access controls, enabling potential privilege escalation on Windows hosts running the 1E Client.
Affected Products
- 1E Client (Nomad module) versions prior to 25.3
- 1E Platform deployments using the affected client
- Windows endpoints running vulnerable 1E Client builds
Discovery Timeline
- 2025-03-12 - CVE-2025-1683 published to NVD
- 2026-01-30 - Last updated in NVD database
Technical Details for CVE-2025-1683
Vulnerability Analysis
The Nomad module of the 1E Client performs file operations as a privileged service on Windows. The module accesses files using paths that an unprivileged local user can influence. Because the module does not validate whether a target path is a symbolic link before performing file operations, an attacker can substitute a controlled path with a link pointing to an arbitrary protected file.
When the privileged service follows the link and performs a delete operation, it does so against the attacker-chosen target rather than the intended file. This allows removal of files the attacker has no direct rights to modify. Local access is required, and the attacker must hold standard user privileges on the system.
Root Cause
The root cause is improper link resolution before file access, classified under CWE-59. The Nomad module opens or deletes files using paths in directories writable by unprivileged users without checking link reparse points. Windows supports several link types — including NTFS junctions, object manager symbolic links, and hard links — any of which can redirect a privileged file operation to an unintended target.
Attack Vector
The attack is local and requires low privileges with no user interaction, matching the MITRE CAPEC-27 leveraging race conditions pattern commonly seen in symlink abuse. An attacker plants a symbolic link in a directory the 1E Client service will operate on. When the service performs its scheduled or triggered file operation, it follows the link and deletes the target file specified by the attacker. Deleting critical system files, security tooling configuration, or DLLs in privileged paths can produce conditions suitable for further escalation.
No public proof-of-concept exploit is currently available for CVE-2025-1683. Technical details on the symlink class of attack are documented in the MITRE CWE-59 definition.
Detection Methods for CVE-2025-1683
Indicators of Compromise
- Unexpected deletion of files in directories typically protected by SYSTEM or TrustedInstaller permissions
- Creation of NTFS junctions or symbolic links in directories accessed by the 1E Client Nomad module
- 1E Client service log entries showing file operations against unexpected paths
- Presence of mklink or CreateSymbolicLink API activity from unprivileged user sessions immediately before privileged file deletions
Detection Strategies
- Monitor file system minifilter events for reparse point creation in directories used by the 1E Client working folders
- Alert on file deletion events by the 1E Client service process where the target path resolves outside its expected working directories
- Correlate symbolic link creation by non-administrative users with subsequent privileged delete operations within a short time window
Monitoring Recommendations
- Enable Windows Sysmon Event IDs 11 (file create) and 23 (file delete) for directories used by the 1E Client
- Track usage of fsutil reparsepoint and the CreateSymbolicLink Windows API by non-administrative users
- Audit the version of the 1E Client deployed across the estate to identify hosts running versions earlier than 25.3
How to Mitigate CVE-2025-1683
Immediate Actions Required
- Upgrade the 1E Client to version 25.3 or later on all Windows endpoints running the Nomad module
- Inventory all hosts with the 1E Client installed and prioritize patching systems exposed to interactive low-privilege users
- Review file system audit logs for evidence of symbolic link abuse against 1E Client working directories
Patch Information
1E has released a fixed version that addresses the improper link resolution flaw. Customers should deploy 1E Client 25.3 or newer. Refer to the vendor security bulletin and the NVD CVE-2025-1683 detail for upgrade guidance and version mapping.
Workarounds
- Restrict interactive logon on systems running the 1E Client to trusted administrative users where operationally feasible
- Apply strict NTFS permissions on 1E Client working directories to prevent link creation by unprivileged accounts
- Enable the Windows symbolic link evaluation policy to disallow non-administrators from creating symbolic links via fsutil behavior set SymlinkEvaluation
# Disable creation and following of local-to-local and remote symbolic links by unprivileged users
fsutil behavior set SymlinkEvaluation L2L:0 R2R:0 L2R:0 R2L:0
# Verify installed 1E Client version on a Windows host
wmic product where "Name like '%%1E Client%%'" get Name,Version
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
