CVE-2022-3592 Overview
A symlink following vulnerability was discovered in Samba that allows authenticated remote users to escape configured share paths and access restricted areas of the file system. This flaw exists in the smbd daemon and can be exploited by users with access to exported file systems via SMB1 unix extensions or NFS. By creating specially crafted symbolic links, attackers can traverse outside the intended share boundaries and potentially access sensitive files on the server.
Critical Impact
Authenticated attackers can bypass share path restrictions to read sensitive files outside configured share boundaries, potentially leading to information disclosure of confidential server data.
Affected Products
- Samba (all affected versions)
- Fedora 36
- Fedora 37
Discovery Timeline
- January 12, 2023 - CVE-2022-3592 published to NVD
- April 8, 2025 - Last updated in NVD database
Technical Details for CVE-2022-3592
Vulnerability Analysis
This vulnerability is classified as a symlink following attack (CWE-61, CWE-59), which allows improper resolution of file paths containing symbolic links. The core issue lies in how Samba's smbd daemon handles symbolic link resolution when processing file access requests from authenticated clients.
When a user creates a symbolic link within an exported share that points to a location outside the configured share path, smbd follows this symlink without proper validation. This effectively allows the user to escape the share's directory jail and access files anywhere on the server's file system where the Samba process has read permissions.
The vulnerability specifically affects environments where SMB1 unix extensions are enabled or where shares are exported via NFS alongside Samba. The network-accessible nature of this vulnerability combined with the requirement for only low-privilege authentication makes it particularly concerning for organizations with shared file servers.
Root Cause
The root cause stems from improper path resolution in Samba's smbd component. When processing file access requests, the daemon fails to adequately validate that symlink targets remain within the configured share path boundaries. This is a classic symlink following vulnerability where the application trusts user-controlled symbolic links without verifying the resolved path stays within allowed directories.
The CWE classifications for this vulnerability are:
- CWE-61: UNIX Symbolic Link (Symlink) Following
- CWE-59: Improper Link Resolution Before File Access ('Link Following')
Attack Vector
The attack requires an authenticated user with access to a Samba share configured with SMB1 unix extensions or exported via NFS. The attacker can exploit this vulnerability by:
- Connecting to the vulnerable Samba share with valid credentials
- Creating a symbolic link within the share that points to a target directory outside the share path (e.g., /etc/, /var/log/, or other sensitive locations)
- Accessing the symlink through the SMB connection, which causes smbd to follow it
- Reading files from the target location that would otherwise be inaccessible
The vulnerability is accessible over the network and requires only low-privilege authentication, with no user interaction needed. The impact is limited to confidentiality as the vulnerability enables unauthorized read access but does not allow modification or deletion of files.
Detection Methods for CVE-2022-3592
Indicators of Compromise
- Presence of symbolic links within Samba shares pointing to paths outside the configured share directory
- Unusual file access patterns in smbd logs showing attempts to access system directories like /etc/, /root/, or /var/
- Authentication events from users followed by access to sensitive configuration files
- Symbolic links created by non-administrative users pointing to ../ relative paths
Detection Strategies
- Monitor Samba audit logs for symlink creation events, particularly those with targets outside share boundaries
- Implement file integrity monitoring on Samba shares to detect new symbolic links
- Configure Samba's vfs objects = full_audit to log all file operations including symlink creation
- Review smbd process access patterns using system call auditing to identify suspicious file reads
Monitoring Recommendations
- Enable verbose logging in Samba configuration with log level = 3 or higher for detailed access tracking
- Configure alerting on symlink operations within shared directories
- Implement regular scans of share directories for symlinks pointing outside allowed paths
- Monitor for SMB1 protocol usage which is required for this exploitation method
How to Mitigate CVE-2022-3592
Immediate Actions Required
- Update Samba to the latest patched version immediately
- Disable SMB1 protocol if not required by setting server min protocol = SMB2 in smb.conf
- Review and remove any existing symlinks within shares that point outside share boundaries
- Enable follow symlinks = no and wide links = no in Samba configuration as a temporary mitigation
Patch Information
Samba has released security patches addressing this vulnerability. Administrators should consult the Samba CVE-2022-3592 Advisory for specific version information and download patched releases.
Additional distribution-specific advisories are available:
Workarounds
- Set follow symlinks = no in smb.conf to prevent Samba from following any symbolic links
- Configure wide links = no to prevent symlinks from pointing outside the share tree
- Disable SMB1 unix extensions by setting unix extensions = no if legacy protocol support is required
- Implement strict share path permissions to limit where symlinks can be created
# Samba configuration hardening example (smb.conf)
[global]
# Disable SMB1 protocol
server min protocol = SMB2
# Disable unix extensions for SMB1 if SMB1 must remain enabled
unix extensions = no
[share]
path = /srv/samba/share
# Prevent symlink following
follow symlinks = no
# Prevent wide links outside share
wide links = no
# Additional access controls
allow symlinks = no
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
