Quantum Secular Labs / Blog / Advisories
CVE-2018-18531: Kaptcha Project: Use of Insufficiently Random Values
CVE-2018-18531 is rated critical with a CVSS v3.0 base score of 9.8 and affects Kaptcha Project. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.
Vulnerability description
text/impl/DefaultTextCreator.java, text/impl/ChineseTextProducer.java, and text/impl/FiveLetterFirstNameTextCreator.java in kaptcha 2.3.2 use the Random (rather than SecureRandom) function for generating CAPTCHA values, which makes it easier for remote attackers to bypass intended access restrictions via a brute-force approach.
Severity breakdown
CVSS v3.0 9.8: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
- Attack complexity: Low. No special conditions; the attack can be repeated reliably.
- Privileges required: None. No account or prior access is needed.
- User interaction: None. No action from any user is needed.
- Scope: Unchanged. Impact stays within the vulnerable component.
- Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
- Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
- Availability impact: High. Total loss of availability; the component can be shut down.
Underlying weakness
CWE-330: Use of Insufficiently Random Values
The product uses insufficiently random numbers or values in a security context that depends on unpredictable numbers.
Affected products
- Kaptcha Project: 2.3.2