📦XSPA: Navigating the Labyrinth of Port Scanning in SSRF

In the intricate landscape of Server-Side Request Forgery (SSRF) exploits, one particular technique stands out as a labyrinthine journey into the heart of network vulnerabilities—Cross-Site Port Attack (XSPA). XSPA empowers attackers to embark on a voyage of port scanning within the confines of the targeted server, revealing the hidden ports and services therein.

Unveiling XSPA: The Art of Port Scanning

XSPA, an acronym that resonates with cyber adventurers, involves scanning a server's open ports, a digital cartographer's quest to chart the territory. The attacker leverages the loopback interface on the server (127.0.0.1 or localhost) while specifying the port of interest. This probing expedition aims to discover exposed services and assess their vulnerabilities. Let's illuminate this with examples:

• Charting the Local Ports: The attacker, armed with knowledge of the server's local interfaces, embarks on port scanning:

https://target.com/page?url=http://localhost:22/

Here, the attacker sails through port 22, mapping the services within the local network.

https://target.com/page?url=http://127.0.0.1:25/

The quest continues as port 25 becomes the next destination for exploration.

• Unearthing Remote Possibilities: XSPA extends its reach beyond the local shores. The attacker sets sail towards distant horizons:

https://target.com/page?url=http://127.0.0.1:3389/

The journey takes them to port 3389, uncovering services that may be vulnerable to exploitation.

• Charting the Unknown: In a daring move, the attacker steers towards uncharted waters by using a variable 'PORT':

https://target.com/page?url=http://localhost:PORT/

Here, 'PORT' symbolizes an open canvas, ready to be painted with the colors of port numbers and exploration.

Beyond Port Scanning: The Expansive Reach of XSPA

XSPA's exploration is not confined to port scanning alone. The attacker, much like an intrepid explorer, might venture further by attempting to ping private IP addresses. These private IP address ranges are often concealed within a network's boundaries:

• Navigating the Private IP Space: The attacker, equipped with knowledge of private IP address ranges, endeavors to map the network's internal layout:

192.168.0.0/16
172.16.0.0/12
10.0.0.0/8

These address ranges represent a treasure trove of information about the internal network, providing insights into its structure and potential vulnerabilities.

Conclusion: The Intrigue of XSPA in SSRF Exploits

As we conclude our exploration of XSPA within the realm of SSRF exploits, we are reminded of the multifaceted nature of network security. XSPA, like an adventurer's compass, points us towards open ports and hidden landscapes, both within the server and the network at large.