CVE-2023-28119: Denial Of Service Via Deflate Decompression Bomb in github.com/crewjam/saml

Background

The github.com/crewjam/saml package is a Go library that provides functionality for processing SAML (Security Assertion Markup Language) messages. It is commonly used in applications that require SAML-based authentication and authorization. The package allows for the parsing, generation, and validation of SAML messages, making it a crucial component in SAML-based systems. However, a vulnerability has been discovered in the package that could lead to a Denial of Service (DoS) attack.

Vulnerability Detail

The vulnerability in github.com/crewjam/saml arises from the improper handling of input data during the decompression process using the Deflate algorithm. The package uses flate.NewReader, which does not limit the size of the input. An attacker can exploit this by sending a large amount of data in the HTTP request, causing the server-side decompression to consume excessive resources. By repeatedly sending the same request, the attacker can trigger a crash, as the operating system kills the process. This vulnerability has a CVSS score of 7.5, indicating a high severity level.

go get github.com/crewjam/saml@v0.5.1

go get github.com/crewjam/saml@v0.4.13

Workaround

As a temporary workaround, developers can implement input size validation at the application level. By checking the size of the input data before passing it to the github.com/crewjam/saml package, developers can prevent excessively large requests from triggering the vulnerability. Here is an example of how to implement input size validation in Go:

import (
    "net/http"
    "io/ioutil"
)

func handleSAMLRequest(w http.ResponseWriter, r *http.Request) {
    maxRequestSize := 1024 * 1024 // 1 MB
    body, err := ioutil.ReadAll(io.LimitReader(r.Body, maxRequestSize))
    if err != nil {
        // Handle error
    }
    // Process the SAML request
}

Conclusion

The vulnerability in github.com/crewjam/saml can lead to a Denial of Service (DoS) attack, potentially causing the affected application or service to become unavailable. It is crucial to update the package to version 0.4.13 or later to mitigate the risk. Implementing input size validation at the application level can serve as a temporary workaround. For further assistance and support in addressing this vulnerability, please contact DevNack.com.

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