vigor2620: Improper Control of Generation of Code
CVE-2023-31447 is a critical-severity improper control of generation of code vulnerability in vigor2620 from DrayTek, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 3.9.8.4 as the first without the flaw, so updating vigor2620 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.94% chance of exploitation within 30 days, higher than 61% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update vigor2620 to 3.9.8.4 or a later version.
- Update Vigor2620 Firmware to 3.9.8.4 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Draytek | vigor2620 | before 3.9.8.4 | 3.9.8.4 |
| Draytek | Vigor2620 Firmware | before 3.9.8.4 | 3.9.8.4 |
| Draytek | Vigor2625 Firmware | Not specified in the record | Not stated |
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
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- 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:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
Official description
user_login.cgi on Draytek Vigor2620 devices before 3.9.8.4 (and on all versions of Vigor2925 devices) allows attackers to send a crafted payload to modify the content of the code segment, insert shellcode, and execute arbitrary code.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Control of Generation of Code
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
How developers prevent this class of flaw
- Refactor your program so that you do not have to dynamically generate code.
- Run your code in a jail or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which code can be executed by your product. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
- Use dynamic tools and techniques that interact with the product using large test suites with many diverse inputs, such as fuzz testing (fuzzing), robustness testing, and fault injection. The product's operation may slow down, but it should not become unstable, crash, or generate incorrect results.
More Improper Control of Generation of Code vulnerabilities (CWE-94)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- gist.github.com/rrrrrrri/013c9eef64b265af4163478bfcf29ff4Third Party Advisory
Other references
- draytek.comProduct
Recent Improper Control of Generation of Code vulnerabilities
- 9.8 Critical severity
- 8.8 High severity
- 8.0 High severity
- 9.8 Critical severity
- 8.8 High severity
- 8.8 High severity
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