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Vdesk Hangupphp3 Exploit Direct

Executive summary

vDesk "HangUpPHP3" refers to a PHP-based exploit chain targeting vDesk web applications (file-sharing/remote desktop type deployments). The exploit enables remote code execution (RCE) by abusing a vulnerable PHP endpoint that improperly handles uploaded or serialized data, allowing an attacker to run arbitrary PHP code on the server. Impact: full application compromise, potential host takeover, data exfiltration, lateral movement. Urgency: high — treat as critical on internet-accessible installs.

Technical Deep Dive: How the Exploit Works

Phase 2: Triggering a Partial Hangup

Instead of terminating the call normally through the VoIP switch, the attacker sends a malformed SIP BYE packet or directly invokes the hangup.php3 endpoint without proper session validation. Example malicious request: vdesk hangupphp3 exploit

POST /telephony/hangup.php3 HTTP/1.1
Host: target.vdesk.com
Cookie: PHPSESSID=malicious123
Content-Type: application/x-www-form-urlencoded

call_id=12345&force=1&sig_type=SIGHUP

Part 4: Why Was This Exploit So Effective?

Several factors contributed to the severity of this vulnerability: Executive summary vDesk "HangUpPHP3" refers to a PHP-based

  1. Lack of Input Validation: No realpath() or basename() checks on the sess parameter.
  2. Register Globals = ON: PHP3 and early PHP4 defaulted to register_globals = On, meaning $session_id could be set via URL without $_GET.
  3. Null Byte Injection: PHP3 allowed null bytes (%00) to terminate strings, effectively ignoring the .php3 extension after a directory traversal.
  4. File Inclusion Without Whitelisting: Any file readable by the web user could be included and executed.

Part 6: Modern Counterparts & Lessons Learned

Although the exact "vdesk hangupphp3 exploit" is extinct in modern web applications (PHP3 died over two decades ago), its class of vulnerability is alive and well. This includes: Part 4: Why Was This Exploit So Effective

  • CWE-98: Improper Control of Filename for Include/Require Statement (PHP File Inclusion).
  • CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
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