SB2020012222 - Denial of service in Trustwave ModSecurity

Description

This security bulletin contains information about 2 secuirty vulnerabilities.

1) Input validation error (CVE-ID: CVE-2019-19886)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input in "Transaction::addRequestHeader" in transaction.cc. A remote attacker can send specially crafted crafted requests to the server and cause a denial of service condition on the target system.

2) Improper handling of exceptional conditions (CVE-ID: CVE-2019-25043)

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to improper handling of errors while parsing key-value pair. A remote attacker can send a specially crafted header to the server and perform a denial of service (DoS) attack, as demonstrated by a "string index out of range" error and worker-process crash for a "Cookie: =abc" header.

Remediation

Install update from vendor's website.

References

• https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-denial-of-service-details-cve-2019-19886/
• https://github.com/SpiderLabs/ModSecurity/issues/2566