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Syntactic Ghost: An Imperceptible General-purpose Backdoor Attacks on Pre-trained Language Models

Core Concepts
The authors propose a novel method, Syntactic Ghost, to achieve invisible and general backdoor implantation in pre-trained language models. By manipulating poisoned samples with different syntactic structures, they outperform previous methods and achieve predefined objectives.
The authors introduce Syntactic Ghost as an imperceptible backdoor attack on pre-trained language models. They manipulate poisoned samples with various syntactic structures to achieve effectiveness, stealthiness, and universality. The method involves contrastive learning and a syntactic-aware module to drive PLMs to learn syntactic knowledge. Experiments show superior performance compared to existing methods across various NLU tasks and PLMs.
Pre-trained language models (PLMs) have been found susceptible to backdoor attacks. Existing PLM backdoors are conducted with explicit triggers under manual alignment. The proposed method achieves invisible and general backdoor implantation through syntactic manipulation. Experiments show that the method outperforms previous methods and achieves predefined objectives.
"The proposed method is generic and imperceptible without any prior knowledge." "When synGhost is adopted on PLMs, the major difference between the implicit triggers and the clean samples now resides in the syntactic structure."

Key Insights Distilled From

by Pengzhou Che... at 03-01-2024
Syntactic Ghost

Deeper Inquiries

How can the concept of invisible triggers be applied in other cybersecurity contexts?

Invisible triggers, as demonstrated in the context of imperceptible backdoors in PLMs, can be applied to various cybersecurity contexts to enhance stealth and effectiveness in attacks. One potential application is in malware detection evasion, where attackers could embed hidden triggers within malicious code to evade traditional detection methods. These triggers could activate specific malicious behaviors only under certain conditions or when triggered by a specific event, making them harder to detect using conventional security measures. Another application could be in phishing attacks, where invisible triggers could be used to bypass email filters and anti-phishing mechanisms. By embedding subtle cues or markers that are only recognizable by the attacker's system, phishing emails could appear legitimate to automated security systems but still carry out malicious actions once opened by the target recipient. Furthermore, invisible triggers could also be utilized in network intrusion scenarios, allowing attackers to create hidden entry points into secure networks that are difficult for traditional intrusion detection systems to identify. By activating these triggers at strategic times or under specific conditions, attackers can gain unauthorized access without raising suspicion.

How might advancements in natural language processing impact the detection of such imperceptible backdoors?

Advancements in natural language processing (NLP) have the potential to significantly impact the detection of imperceptible backdoors embedded within PLMs. As NLP models become more sophisticated and capable of understanding complex linguistic structures and nuances, they can be leveraged for more effective anomaly detection and pattern recognition tasks related to identifying hidden triggers or suspicious behavior within text data. One way advancements in NLP can aid in detecting imperceptible backdoors is through enhanced semantic analysis capabilities. Advanced NLP models can analyze text at a deeper level, uncovering subtle patterns or anomalies that may indicate the presence of hidden triggers or malicious intent within textual data. Additionally, improvements in contextual understanding and sentiment analysis offered by advanced NLP models enable better identification of abnormal language usage or inconsistencies that may signal the presence of an imperceptible backdoor. These models can help flag suspicious text passages for further investigation and analysis. Moreover, advancements such as syntactic-aware probing layers introduced for enhancing sensitivity towards syntactic knowledge can assist in detecting deviations from expected linguistic structures caused by imperceptible backdoors. By leveraging these capabilities along with techniques like contrastive learning for feature alignment across different syntactic templates, NLP models can improve their ability to detect subtle manipulations introduced by hidden triggers. Overall, advancements in natural language processing offer promising avenues for improving the detection capabilities against imperceptible backdoors by enabling more nuanced analysis of textual content and underlying linguistic features.