A common type of race condition where a resource is checked, but changed by another process before it is used. Anatomy of a Race Condition Attack
# Exploit code def exploit(chatbot, malicious_payload): # Create a new thread for the malicious payload malicious_thread = threading.Thread(target=chatbot.execute_task, args=(malicious_payload,)) malicious_thread.start()
while true; do /opt/vuln_binary /tmp/link 2>/dev/null done race condition hackviser
The lab on Hackviser is widely considered a solid, well-structured module . It is part of the CAPT (Certified Associate Penetration Tester) path, which users praise for its balance between beginner-friendly guidance and realistic difficulty. Key Highlights of the Lab
There are several types of race conditions, including: A common type of race condition where a
Usage: ./vuln_binary <file_to_read>
You begin by analyzing the application's business logic. Which actions involve checks and updates? Common targets are coupon redemption, balance transfers, file uploads, or voting systems. The goal is to find an endpoint where a "check" (e.g., verifying a balance) is performed immediately before an "action" (e.g., updating it) without proper locking. A successful write-up of a race condition often starts by mapping these endpoints. Key Highlights of the Lab There are several
: Approves the deduction and sends $100 because its "check" phase was already validated.
Once the race is won, the hackviser injects a payload (e.g., symlink to /etc/shadow , extra transaction). The payload is decoupled from the race trigger to avoid detection.
You’ve withdrawn $200 from a $100 balance because the "Check" for Thread B happened before Thread A finished its "Use." 2. Common Attack Vectors
Fixing a race condition requires ensuring that operations on shared resources are safe from concurrent interference. Implement Atomic Operations