Spam Filter Preprocessing for Disguised Invisible Characters
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Solution Overview
Problem
Spammers employ techniques to deceive spam filters by breaking electronic messages into visible and invisible portions, where the invisible portion contains innocuous words that mislead filters into categorizing the message as clean, despite the presence of spam words in the visible portion.
Innovation Solution
A method that identifies and deletes portions of an electronic message where the foreground and background colors are negligible, ensuring that only visible characters are processed by the spam filter, thereby preventing spammers from disguising spam messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spam filters process all characters in an electronic message including invisible portions, then the filter may be deceived by disguised innocuous words, but processing only visible characters reduces detection accuracy
Solution Approach 1:
The patent segments the electronic message into visible and invisible portions based on color characteristics. It identifies portions where foreground and background colors are substantially similar (invisible to humans) and separates them from visible portions. The spam filter then processes only the visible portions, preventing disguised words in invisible portions from deceiving the filter while maintaining accurate spam detection.
Solution Approach 2:
The patent introduces an intermediary component that acts as a preprocessing layer between the message and the spam filter. This intermediary analyzes color characteristics of message portions, determines visibility based on color difference thresholds, and selectively passes only visible portions to the spam filter. This intermediary prevents the filter from being deceived by invisible disguised characters while preserving detection accuracy.
2Productivity
If the spam filter analyzes the entire message including invisible portions, then it processes more data, but this allows spammers to manipulate filter decisions with disguised words
Solution Approach 1:
The patent extracts and removes invisible portions from the message before submission to the spam filter. By taking out the deceptive invisible characters that spammers use to manipulate filter decisions, the system prevents these portions from affecting spam classification. This extraction maintains processing efficiency while eliminating the reliability issue of filter manipulation.
3Device complexity
If visible and invisible message portions are treated equally by the spam filter, then the filter is simpler to implement, but spammers can disguise spam words as innocuous text
Solution Approach 1:
The patent performs preliminary action by analyzing and classifying message portions as visible or invisible before the spam filter processes the message. This preprocessing step identifies portions where foreground and background colors are substantially similar and excludes them from filter analysis. By performing this action in advance, the system prevents spammers from successfully disguising spam words without significantly increasing overall system complexity.
Data Source
AI summary
Computer-implemented methods, apparati, and computer-readable media for countering spam that disguises characters within an electronic message (1). A method embodiment of the present invention comprises locating (36) portions of an electronic message (1) where the difference between foreground color and background color is negligible; deleting (37) from the electronic message (1) foreground characters from said portions, to form a redacted electronic message; and forwarding (33) the redacted electronic message to a spam filter (23).