CVE-2017-18638 in Graphite
Summary
by MITRE
send_email in graphite-web/webapp/graphite/composer/views.py in Graphite through 1.1.5 is vulnerable to SSRF. The vulnerable SSRF endpoint can be used by an attacker to have the Graphite web server request any resource. The response to this SSRF request is encoded into an image file and then sent to an e-mail address that can be supplied by the attacker. Thus, an attacker can exfiltrate any information.
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Analysis
by VulDB Data Team • 01/08/2024
The vulnerability identified as CVE-2017-18638 represents a critical server-side request forgery flaw within the Graphite monitoring platform, specifically affecting versions through 1.1.5. This vulnerability exists within the send_email functionality located in graphite-web/webapp/graphite/composer/views.py, where the application fails to properly validate and sanitize user-supplied input before using it in HTTP requests. The flaw allows attackers to manipulate the email sending mechanism to make the Graphite web server initiate requests to arbitrary internal or external resources, creating a dangerous attack vector that bypasses normal network security controls.
The technical implementation of this vulnerability stems from improper input validation in the email composition and sending process, which directly maps to CWE-918 Server-Side Request Forgery. When an attacker crafts a malicious email request, the Graphite web application processes this input without adequate sanitization, enabling the server to make HTTP requests to targets specified by the attacker. This vulnerability operates at the application layer and can be exploited through the web interface, making it particularly dangerous as it allows attackers to leverage the Graphite server's network access privileges to reach internal systems that would otherwise be protected by firewalls or network segmentation.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the capability to perform extensive reconnaissance and data exfiltration activities. Attackers can use this vector to probe internal network services, access sensitive information stored on internal servers, and potentially escalate their attack by using the compromised Graphite server as a pivot point for further network exploration. The vulnerability's exploitation capability is amplified by the fact that the response from these SSRF requests is encoded into image files and sent via email, which can be configured to target any email address specified by the attacker, making it difficult to detect and trace the malicious activity.
Security practitioners should implement immediate mitigations including input validation and sanitization of all user-supplied parameters in email-related functions, network segmentation to restrict the Graphite server's access to internal resources, and the implementation of web application firewalls to detect and block suspicious requests. The vulnerability aligns with ATT&CK technique T1071.004 Application Layer Protocol: DNS, as attackers may use DNS resolution through the SSRF capability to gather information about internal network resources. Organizations should also consider implementing network monitoring to detect unusual outbound requests from the Graphite server and ensure that the application is updated to a patched version that properly validates all input parameters before processing them in network requests. The fix typically involves implementing strict validation of URLs and ensuring that only trusted domains are accessible through the email sending functionality.