Sandbox File Hash Comparison for Time-Delay Attack Detection
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Solution Overview
Problem
Current email security solutions employing sandboxing are vulnerable to time-delay based network attacks where malware authors deceive systems by initially pointing a link to a benign file, which is later replaced with a malicious file, evading detection and allowing malware to execute on the recipient's system.
Innovation Solution
The system receives an email with a potentially malicious link, evaluates the file it points to at two different times, generates hash values for each evaluation, and compares them to detect if the file has been replaced, thereby treating the file as malicious if the hash values differ, and taking appropriate actions such as blocking the email or alerting administrators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sandboxing is used to detect malware in emails, then detection accuracy is improved, but time-delay based attacks can evade detection by replacing files after initial analysis
Solution Approach 1:
The system performs preliminary file analysis at multiple time points before final delivery decisions are made. By conducting initial sandboxing at receipt and then re-evaluating the same URL at a later time, the system proactively detects file replacements before recipients interact with the email, preventing the attack from executing.
Solution Approach 2:
The system implements periodic re-analysis of URLs at scheduled time intervals after initial email receipt. This periodic action creates multiple detection opportunities, allowing the system to catch file replacements that occur between initial analysis and final delivery, thereby closing the time window exploitability.
2Productivity
If emails are analyzed quickly through sandboxing, then productivity is improved, but detection precision deteriorates due to insufficient analysis time
Solution Approach 1:
The system performs preliminary quick assessment of files through sandboxing at email receipt to enable rapid initial processing. This preliminary action allows most benign emails to be processed quickly while maintaining the capability for deeper analysis when needed.
Solution Approach 2:
The system implements feedback loops where URLs are re-analyzed at later time points based on initial analysis results and timing patterns. This feedback mechanism allows the system to adjust analysis depth and timing dynamically, improving detection precision without significantly impacting overall processing throughput.
3Measurement precision
If multiple time-point evaluations are performed to detect file replacements, then detection precision is improved, but device complexity increases
Solution Approach 1:
The system uses a universal sandboxing infrastructure that serves multiple functions: initial file analysis, periodic re-evaluation, and threat intelligence gathering. By making the sandbox environment multi-functional and reusable across different time points and email analyses, the system achieves enhanced detection precision without proportionally increasing complexity.
Solution Approach 2:
The system creates simplified copies or representations of file states at different time points (such as hash values, sandbox behavior profiles, or metadata) rather than maintaining full duplicate analysis environments. This copying approach enables comparison across time points while keeping the actual system complexity manageable.
Data Source
AI summary
Systems and methods are described for mitigation of time-delay based network attacks that seek to avoid detection by email security solutions employing sandboxing. According to one embodiment, a potentially malicious link associated with a communication is received from a computer system by a sandbox device. A link evasion technique, in which a first file to which the potentially malicious link points to at a first time is replaced with a second file on or before a second time, is subverted by the sandbox by evaluating the potentially malicious link at multiple times including generating a first hash value of the contents of the first file, generating a second hash value of the contents of the second file, assigning a threat level to the communication when the hash values differ, and informing the computer system of the threat level assigned to the communication.