WS_FTP Server: Improper Limitation of a Pathname to a Restricted Directory
CVE-2023-42657 is a critical-severity improper limitation of a pathname to a restricted directory vulnerability in WS_FTP Server from Progress Software, with a CVSS 3.1 base score of 9.6 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 8.8.2, 8.7.4 as the first without the flaw, so updating WS_FTP Server to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 16% chance of exploitation within 30 days, which is in the top 3.04% of all scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update WS_FTP Server to 8.8.2 or 8.7.4, whichever matches your release line, or a later version.
- Read the advisory on community.progress.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Progress Software | WS_FTP Server | 8.8.0 up to, but not including, 8.8.2; 8.7.0 up to, but not including, 8.7.4 | 8.8.2, 8.7.4 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.9 | Critical | CNA (progress.com) |
| CVSS 3.1 | 9.6 | Critical | NVD |
Official description
In WS_FTP Server versions prior to 8.7.4 and 8.8.2, a directory traversal vulnerability was discovered. An attacker could leverage this vulnerability to perform file operations (delete, rename, rmdir, mkdir) on files and folders outside of their authorized WS_FTP folder path. Attackers could also escape the context of the WS_FTP Server file structure and perform the same level of operations (delete, rename, rmdir, mkdir) on file and folder locations on the underlying operating system.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
- progress.com/ws_ftpProduct
Other vulnerabilities in WS_FTP Server
- 7.7 High severity
- 7.1 High severity
- 7.5 High severity
- 8.1 High severity
- 7.5 High severity
- 9.9 Critical severity
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 7.8 High severity
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
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