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Sihat Afnan

Graduate Fellow at UC Irvine

Hi! I am Sihat Afnan, a PhD student in the CSE Department of University of California, Irvine. I have graduate from the Department of Computer Sciences Bangladesh University of Engneering and technology(BUET).

I enjoy outdoor activities (e.g. jogging, travelling), reading non-fiction, Op-Eds, and listening to qawali music.

Interests

  • Systems Security
  • Network Security

Education

  • PhD in Computer Science (2024 - Present)

    University of California, Irvine

  • Bachelor of Science in Computer Science (2018 - 2023)

    Bangaldesh University of Engineering and Technology




Professional Experience

Lecturer

Department of CSE
School of Data and Sciences
BRAC University

Taught courses on Computer Architecture, Microprocessor, Operating Systems and Discrete Mathematics

Machine Learning Engineer

Deployed Mathematical models, built machine learning tools and devised financial engineering solutions




Research Experience

LogShield: A Transformer-based APT Detection System Leveraging Self-Attention

Abstract—A framework designed to detect APT attack patterns leveraging the power of self-attention in transformers. We incorporate customized embedding layers to effectively capture the context of event sequences derived from provenance graphs. While acknowledging the computational overhead associated with training transformer networks, our framework surpasses existing LSTM and Language models regarding APT detection performance. We integrated the model parameters and training procedure from the RoBERTa model and conducted extensive experiments on well-known APT datasets (DARPA OpTC and DARPA TC E3). Our framework achieved superior F1 scores of 98\% and 95\% on the two datasets respectively, surpassing the F1 scores of 96\% and 94\% obtained by LSTM models. Our findings suggest that LogShield's performance benefits from larger datasets and demonstrates its potential for generalization across diverse domains.

Status : Under review, [ArXiv Version]

Protocol State Fuzzing of 4G LTE Devices

We will be analyzing several 4G LTE COTs devices to detect any noncompliant behavior that deviates from the protocol specification. Active Automata Learning is being used to infer finite state machine from 4G LTE protocol implementation. The deviation will be detected from the learned FSMs and the protocol specifications. This is a collaboration project under the supervision of Professor Md. Shohrab Hossain.

Status : Ongoing

Bangla Grammatical Error Detection Leveraging Transformer-based Token Classification

Abstract— Bangla is the seventh most spoken language by a total number of speakers in the world, and yet the development of an automated grammar checker in this language is an understudied problem. Bangla grammatical error detection is a task of detecting sub-strings of a Bangla text that contain grammatical, punctuation, or spelling errors, which is crucial for developing an automated Bangla typing assistant. Our approach involves breaking down the task as a token classification problem and utilizing state-of-the-art transformer-based models. Finally, we combine the output of these models and apply rule-based post-processing to generate a more reliable and comprehensive result. Our system is evaluated on a dataset consisting of over 25,000 texts from various sources. Our best model achieves a Levenshtein distance score of 1.04. Finally, we provide a detailed analysis of different components of our system.

Status : In Preparation for ACL Workshop, [pdf]




Coursework

Course Title Instructor Keywords Projects
Computer Security Md Shohrab Hossain Cryptography, Authentication, PKI, Access Control, DDoS, BGP, DNS Security, TLS/SSL, Buffer Overflow, CSRF Buffer Overflow Exploitation, CSRF Defense, Morris Worm Attack
Computer Networks ABM Alim Al Islam (Razi) OSI, TCP/IP, HTTPS, Encryption, Firewall, VPN, Congestion Control, RTT, SDN, NFV RTT RTO Estimation, Building Firewall
Operating Systems Rezwana Reaz Scheduling, Virtualization, Concurrency, File Systems, Storage XV6, Scheduling, Memory Management Module
Machine Learning Mohammad Saifur Rahman DNN, RNN, LSTM, LLM, Transformer, Reinforcement Learning CNN implementation from scratch, EM Algorithm Simulation, Crackle detection from Mel-Spectogram



Projects

 
 
 
 
 

Flow classification on Programmable Data Plane using P4 Switch

Classifying network flows at an early stage primarily based on size of the flow, count of packets, inter-arrival time, and duration of the flow. The ML technique considered is decision trees since it can be easily implemented in PISA Architecture.
[Code]

 
 
 
 
 

Improving RTT & RTO

Open source implementation of Peak-Hopper: A New End-to-End Retransmission Timer for Reliable Unicast Transport. It improves the performance of retransmission timer specified in [RFC2988] using the network simulator NS3.
[Code]

 
 
 
 
 

Bengali Complex Named Entity Recognition

Identifications and classification of named entities in Bangla language texts using the BERT model. The project is designed to be used in various applications such as text analytics and information retrieval systems.
[Code]

 
 
 
 
 

Operating Systems Projects

Course Project

Adding syscall, threading and scheduling in XV6, implementing Linux shell, implementation of Memory Management Module of XV6.
[Code]

 
 
 
 
 

Pipelined MIPS-like Processor

Course Project

Implemented an 8-bit processor that supports pipelined datapath for a subset of MIPS instruction set.
[Code]

 
 
 
 
 

A Smart Stick for Blind People with object detection and direction guidance

Course Project

Built a SmartStick for the blind with an embedded system constructed of ATMega32 microcontroller and various sensors mounted on it for obstacle detection and direction guidance.
[Demo]

 
 
 
 
 

Ray Tracing from scratch using OpenGL

Course Project

A ray tracer shoots rays from the observer’s eye through a screen and into a scene of objects. It calculates the ray’s intersection with objects, finds the nearest intersection and calculates the color of the surface according to its material and lighting conditions.
[Code]







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Awards

  • University Dean's List Scholarship (BUET), 2019-2023
  • University Merit Scholarship (BUET), 2018-2023
  • Champion in an international Grammatical Error Detection Competition
  • 2nd Runner Up in NLP Hackathon-2023 hosted by Bangladesh Open Source Network
  • 1st Runner Up in HackNSU 2020 organized by NSU ACM Student Chapter
  • Placed in Top Seven of HackTheVerse 2020 hosted by IIT,DU
  • Program Committee member in BEA-ACL 2023 Conference Workshop
  • Talentpool Scholarship (HSC/O Level) ; 8th position in Dhaka Board
  • Talentpool Scholarship (SSC/A level) ; 20th position in Dhaka Board
  • Coordinator and Problem Setter in ICT Olympiad of St. Joseph High School, Dhaka



Contact

  • sihat.afnan@bracu.ac.bd
  • DM Me
  • BRAC University, Department of Computer Sciences and Engineering, School of Data and Sciences, 1 Bir Uttam Rafiqul Islam Ave, Dhaka 1212