Chen Hajaj

Dr. Chen Hajaj

orcid

Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
2 November 2022 in Computers & Security
Verified
Journal Article
Closed access
ALAdi Lichy
Adi Lichy
OBOfek Bader
Ofek Bader
RDRan Dubin
Ran Dubin
ADAmit Dvir
Amit Dvir
CHChen Hajaj
Chen Hajaj

10 June 2023 in Nutrients
Verified
Journal Article
Open access
PDF file
OROrit Raphaeli
Orit Raphaeli
LSLiran Statlender
Liran Statlender
CHChen Hajaj
Chen Hajaj
IBItai Bendavid
Itai Bendavid
AGAnat Goldstein
Anat Goldstein
PSPierre Singer
Pierre Singer
Background: The association between gastrointestinal intolerance during early enteral nutrition (EN) and adverse clinical outcomes in critically ill patients is controversial. We aimed to assess the prognostic value of enteral feeding intolerance (EFI) markers during early ICU stays and to predict early EN failure using a machine learning (ML) approach. Methods: We performed a retrospective analysis of data from adult patients admitted to Beilinson Hospital ICU between January 2011 and December 2018 for more than 48 h and received EN. Clinical data, including demographics, severity scores, EFI markers, and medications, along with 72 h after admission, were analyzed by ML algorithms. Prediction performance was assessed by the area under the receiver operating characteristics (AUCROC) of a ten-fold cross-validation set. Results: The datasets comprised 1584 patients. The means of the cross-validation AUCROCs for 90-day mortality and early EN failure were 0.73 (95% CI 0.71–0.75) and 0.71 (95% CI 0.67–0.74), respectively. Gastric residual volume above 250 mL on the second day was an important component of both prediction models. Conclusions: ML underlined the EFI markers that predict poor 90-day outcomes and early EN failure and supports early recognition of at-risk patients. Results have to be confirmed in further prospective and external validation studies.

21 March 2022 in Electronics
Verified
Journal Article
Open access
PDF file
CHChen Hajaj
Chen Hajaj
NHNitay Hason
Nitay Hason
ADAmit Dvir
Amit Dvir
Malicious domains are increasingly common and pose a severe cybersecurity threat. Specifically, many types of current cyber attacks use URLs for attack communications (e.g., C&C, phishing, and spear-phishing). Despite the continuous progress in detecting cyber attacks, there are still critical weak spots in the structure of defense mechanisms. Since machine learning has become one of the most prominent malware detection methods, a robust feature selection mechanism is proposed that results in malicious domain detection models that are resistant to evasion attacks. This mechanism exhibits a high performance based on empirical data. This paper makes two main contributions: First, it provides an analysis of robust feature selection based on widely used features in the literature. Note that even though the feature set dimensional space is cut by half, the performance of the classifier is still improved (an increase in the model’s F1-score from 92.92% to 95.81%). Second, it introduces novel features that are robust with regard to the adversary’s manipulation. Based on an extensive evaluation of the different feature sets and commonly used classification models, this paper shows that models based on robust features are resistant to malicious perturbations and concurrently are helpful in classifying non-manipulated data.

23 May 2022 in IEEE Access
Verified
Journal Article
Open access
RBRotem Bar
Rotem Bar
CHChen Hajaj
Chen Hajaj
Traffic detection has attracted much attention in recent years, playing an essential role in intrusion detection systems (IDS). This paper proposes a new approach for traffic detection at the packet level, inspired by natural language processing (NLP), using simple contrastive learning of sentence embeddings (SimCSE) as an embedding model. The new approach can learn the features of traffic from raw packet data. Experiments were conducted on two well-known datasets to evaluate our approach. For detecting malicious activity, our model achieved an accuracy of 99.99% on the USTC-TFC2016 dataset, whereas for detecting virtual private network (VPN) activity, our model achieved an accuracy of 99.98% on the ISCXVPN2016 dataset. Furthermore, the resulting model was found to be robust based on zero-day attack detection, which shows the model’s ability to detect attacks that have not been seen before. Experiments show that our approach can effectively detect network traffic and outperforms many other state-of-the-art methods.

25 June 2020
Verified
Book Chapter
Closed access
PDF file
HBHarel Berger
Harel Berger
CHChen Hajaj
Chen Hajaj
ADAmit Dvir
Amit Dvir

1 September 2020 in Computers & Security
Verified
Journal Article
Closed access
ADAmit Dvir
Amit Dvir
AMAngelos K. Marnerides
Angelos K. Marnerides
RDRan Dubin
Ran Dubin
NGNehor Golan
Nehor Golan
CHChen Hajaj
Chen Hajaj