Threat Intel

‘CVE-2025-58034 is an OS command injection vulnerability (CWE-78) in Fortinet FortiWeb, allowing an authenticated attacker to execute unauthorized code on the system through crafted HTTP requests or CLI commands. It affects versions including FortiWeb 8.0.0-8.0.1, 7.6.0-7.6.5, 7.4.0-7.4.10, 7.2.0-7.2.11, and 7.0.0-7.0.11. The vulnerability has a CVSSv3 score of 6.7 (medium severity) and has been observed exploited in the wild, prompting its addition to CISA’s Known Exploited Vulnerabilities catalog.’

Payload

GET /api/v2.0/cmdb/user/saml-user/../../../../../cgi-bin/fwbcgi HTTP/1.1
Host: [redacted]
Accept-Encoding: identity
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:94.0) Gecko/20100101 Firefox/94.0
CGIINFO: eyJ1c2VybmFtZSI6ICJhZG1pbiIsICJwcm9mbmFtZSI6ICJwcm9mX2FkbWluIiwgInZkb20iOiAicm9vdCIsICJsb2dpbm5hbWUiOiAiYWRtaW4ifQ==

AI Based Analysis

Breakdown of the Provided HTTP Payload

This HTTP request appears to be an exploit attempt targeting a vulnerability in Fortinet FortiWeb appliances (likely CVE-2025-64446, based on matching patterns in public analyses, though labeled as CVE-2025-58034 in the query—note that CVE-2025-58034 is a separate OS command injection issue, while this payload aligns with path traversal and authentication bypass in CVE-2025-64446). It combines directory traversal to access a restricted internal component with forged authentication data to impersonate an administrator. Below, I’ll break it down component by component, explaining the purpose and potential impact. This is for educational purposes only—do not test or use this on unauthorized systems, as it could violate laws.

1. Request Line

GET /api/v2.0/cmdb/user/saml-user/../../../../../cgi-bin/fwbcgi HTTP/1.1
  • Method: GET
  • A simple read operation, often used for testing vulnerability presence without modifying the system. If the server responds with HTTP 200 OK, it indicates the path traversal succeeded and the endpoint is accessible (meaning the device is likely vulnerable). For full exploitation (e.g., creating accounts or executing commands), a POST method with a JSON body is typically used instead.
  • URI Path: /api/v2.0/cmdb/user/saml-user/../../../../../cgi-bin/fwbcgi
  • Starting Point: /api/v2.0/cmdb/user/saml-user
    • This is a legitimate API endpoint in FortiWeb for managing SAML users (part of the Configuration Management Database, or CMDB). It’s chosen as a base because it’s accessible to authenticated users and serves as an entry point for routing requests internally.
  • Path Traversal: /../../../../../
    • The sequence of ../ (dot-dot-slash) is a classic directory traversal technique. Each ../ moves up one directory level in the file system.
    • Here, there are 5 levels of traversal (../../../../../ counts as 5 ups, since the last / starts the next segment).
    • Purpose: Bypasses normal API restrictions to navigate from the API directory up to the root or a parent level, then down to a restricted internal directory (/cgi-bin/).
  • Target Endpoint: cgi-bin/fwbcgi
    • cgi-bin/ is a common directory for CGI (Common Gateway Interface) scripts, which are executables that handle dynamic web requests.
    • fwbcgi is an internal FortiWeb CGI binary (executable) responsible for processing backend requests, including authentication and command handling. It’s not meant to be directly accessible from external APIs, but the traversal routes the request directly to it, bypassing frontend checks.
    • Once reached, fwbcgi processes the request using its internal functions like cgi_auth() and cgi_process(), which can lead to privileged operations if authentication is bypassed.
  • Protocol: HTTP/1.1
  • Standard HTTP version, nothing unusual here.

2. Headers

Headers provide metadata about the request. These are crafted to mimic a legitimate browser request while including the key exploit element.

  • Host: [redacted]
  • Specifies the target server’s hostname or IP. Redacted here for privacy, but in a real exploit, this would be the vulnerable FortiWeb device’s address.
  • Accept-Encoding: identity
  • Tells the server not to compress the response (e.g., no gzip). This ensures the response is returned in plain, uncompressed form, making it easier to analyze or avoiding potential issues with encoded data.
  • User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:94.0) Gecko/20100101 Firefox/94.0
  • Identifies the client as an older version of Firefox (release 94.0 from 2021) running on a 64-bit Linux system.
  • Purpose: Blends in with normal traffic to evade basic logging or WAF rules that might flag suspicious agents (e.g., curl or Python scripts). Using an outdated UA might also target legacy compatibility in the server.
  • CGIINFO: eyJ1c2VybmFtZSI6ICJhZG1pbiIsICJwcm9mbmFtZSI6ICJwcm9mX2FkbWluIiwgInZkb20iOiAicm9vdCIsICJsb2dpbm5hbWUiOiAiYWRtaW4ifQ==
  • This is the critical exploit header.
  • Value Breakdown:
    • It’s a Base64-encoded string.
    • Decoded: {"username": "admin", "profname": "prof_admin", "vdom": "root", "loginname": "admin"}
    • This is a JSON object with fields for user impersonation.
    • username and loginname: Set to “admin” to impersonate the built-in administrator account.
    • profname: “prof_admin” refers to the super-admin profile in FortiWeb, granting full privileges.
    • vdom: “root” specifies the root Virtual DOM (a Fortinet concept for multi-tenancy isolation), allowing access to the primary configuration.
  • Role in Exploit:
    • The fwbcgi binary’s cgi_auth() function doesn’t enforce standard authentication (e.g., sessions or passwords). Instead, it trusts and parses the CGIINFO header (extracted from HTTP_CGIINFO internally).
    • Process: Base64-decode → Parse as JSON → Use values to set a login context (set_login_context_vsa()) that impersonates the specified user.
    • Result: The request runs with admin privileges, bypassing any need for real credentials.

3. Overall Exploit Mechanism and Impact

  • How It Works Together:
  1. The path traversal allows unauthorized access to fwbcgi, which is normally protected.
  2. Once there, the CGIINFO header fools the auth function into thinking the request is from an admin.
  3. With GET, this might just confirm access (e.g., for reconnaissance). But in a full attack, switching to POST with a JSON body (e.g., {"data": {"name": "attacker", "password": "pass", "access-profile": "prof_admin"}}) could create a new admin account or execute OS commands if combined with command injection vectors.
  • Potential Impact:
  • Authentication bypass leading to full admin control.
  • Persistence via rogue accounts.
  • If escalated (e.g., via command injection in CVE-2025-58034), could allow arbitrary code execution on the system.
  • This has been exploited in the wild to compromise FortiWeb devices.

Summary

The data here is from https://defusedcyber.com and you can see how using honeypots enables us to track and monitor what payloads threat actors are using against what targets.

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