SSRF via Proxy Hijacking in Wallos search.php Before

Executive Summary

CVE-2026-33407 is a critical Server-Side Request Forgery (SSRF) vulnerability in the Wallos package versions up to 4.6.2, specifically in the endpoint endpoints/logos/search.php.

The vulnerability occurs because this endpoint accepts the HTTP_PROXY and HTTPS_PROXY environment variables without validation and directly uses them to configure proxy settings in cURL requests.

Attackers can exploit this by controlling DNS resolution targets through user-supplied search terms, which the server processes without proper validation, enabling them to hijack proxy configurations and trigger outbound requests to arbitrary domains.

• Access internal network services if the proxy routes internally.
• Perform DNS-based out-of-band attacks for data exfiltration.
• Enumerate cloud metadata services (e.g., 169.254.169.254).
• Conduct SSRF chain attacks in cloud environments.
• Perform DNS rebinding attacks.

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Impact Analysis

This vulnerability can have serious impacts including unauthorized access and reconnaissance of internal network services, which are normally protected from external access.

Attackers can exfiltrate sensitive data using DNS-based out-of-band techniques.

It allows enumeration of cloud metadata services, potentially exposing sensitive cloud instance information.

The vulnerability can be used to chain SSRF attacks in cloud environments, increasing the attack surface and potential damage.

Overall, it can lead to significant security breaches including data leakage and unauthorized internal network access.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by monitoring outbound DNS queries triggered by the vulnerable endpoint when processing user-supplied search terms. A proof of concept involves setting up a DNSLog listener to observe DNS resolution requests initiated by the server.'}, {'type': 'paragraph', 'content': 'Specifically, sending crafted search queries to the vulnerable endpoint `endpoints/logos/search.php` with controlled DNS names can trigger outbound DNS requests observable on a DNSLog platform.'}, {'type': 'paragraph', 'content': 'Commands to detect this might include using tools like curl or wget to send requests to the vulnerable endpoint with payloads that cause DNS lookups, and monitoring DNS logs or using DNSLog services to capture these outbound DNS queries.'}, {'type': 'list_item', 'content': 'Set up a DNSLog listener or use a DNS monitoring tool to capture outbound DNS requests.'}, {'type': 'list_item', 'content': "Send HTTP GET requests to the vulnerable endpoint with search terms designed to trigger DNS resolution, e.g., using curl: `curl 'http://<wallos-server>/endpoints/logos/search.php?search=attacker-controlled-domain.com'`."}, {'type': 'list_item', 'content': 'Check DNS logs or DNSLog platform for any outbound DNS queries to attacker-controlled domains.'}] [1]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'Immediate mitigation steps include disabling or validating the `HTTP_PROXY` and `HTTPS_PROXY` environment variables before they are used by the vulnerable endpoint.'}, {'type': 'paragraph', 'content': 'Explicitly disable proxy usage in the code by setting cURL options to prevent proxy hijacking.'}, {'type': 'list_item', 'content': "Disable proxy usage by adding `curl_setopt($ch, CURLOPT_PROXY, '')` and `curl_setopt($ch, CURLOPT_NOPROXY, '*')` in the code handling the requests."}, {'type': 'list_item', 'content': 'Validate or sanitize the `HTTP_PROXY` and `HTTPS_PROXY` environment variables to ensure they cannot be manipulated by attackers.'}, {'type': 'list_item', 'content': 'Employ a centralized SSRF validation helper (e.g., `ssrf_helper.php`) to consistently validate URLs and prevent SSRF attacks.'}, {'type': 'paragraph', 'content': 'Ultimately, upgrade Wallos to version 4.7.0 or later, where this vulnerability has been patched.'}] [1]

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