Elif Ustundag Soykan

Elif Ustundag Soykan


Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

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

Representative Publications

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14 August 2020 in IEEE Access
Verified
Journal Article
Open access
ZBZeki Bilgin
Zeki Bilgin
MEMehmet Akif Ersoy
Mehmet Akif Ersoy
ESElif Ustundag Soykan
Elif Ustundag Soykan
ETEmrah Tomur
Emrah Tomur
PCPinar Comak
Pinar Comak
LKLeyli Karacay
Leyli Karacay
As the role of information and communication technologies gradually increases in our lives, software security becomes a major issue to provide protection against malicious attempts and to avoid ending up with noncompensable damages to the system. With the advent of data-driven techniques, there is now a growing interest in how to leverage machine learning (ML) as a software assurance method to build trustworthy software systems. In this study, we examine how to predict software vulnerabilities from source code by employing ML prior to their release. To this end, we develop a source code representation method that enables us to perform intelligent analysis on the Abstract Syntax Tree (AST) form of source code and then investigate whether ML can distinguish vulnerable and nonvulnerable code fragments. To make a comprehensive performance evaluation, we use a public dataset that contains a large amount of function-level real source code parts mined from open-source projects and carefully labeled according to the type of vulnerability if they have any. We show the effectiveness of our proposed method for vulnerability prediction from source code by carrying out exhaustive and realistic experiments under different regimes in comparison with state-of-art methods.

5 September 2022 in IEEE Access
Verified
Journal Article
Open access
ESElif Ustundag Soykan
Elif Ustundag Soykan
LKLeyli Karacay
Leyli Karacay
FKFerhat Karakoc
Ferhat Karakoc
ETEmrah Tomur
Emrah Tomur
As machine learning and artificial intelligence (ML/AI) are becoming more popular and advanced, there is a wish to turn sensitive data into valuable information via ML/AI techniques revealing only data that is allowed by concerned parties or without revealing any information about the data to third parties. Collaborative ML approaches like federated learning (FL) help tackle these needs and concerns, bringing a way to use sensitive data without disclosing critically sensitive features of that data. In this paper, we provide a detailed analysis of state of the art for collaborative ML approaches from a privacy perspective. A detailed threat model and security and privacy considerations are given for each collaborative method. We deeply analyze Privacy Enhancing Technologies (PETs), covering secure multi-party computation (SMPC), homomorphic encryption (HE), differential privacy (DP), and confidential computing (CC) in the context of collaborative ML. We introduce a guideline on the selection of the privacy preserving technologies for collaborative ML and privacy practitioners. This study constitutes the first survey to provide an in-depth focus on collaborative ML requirements and constraints for privacy solutions while also providing guidelines on the selection of PETs.

1 June 2021 in Sustainable Energy, Grids and Networks
Verified
Journal Article
Closed access
ESElif Ustundag Soykan
Elif Ustundag Soykan
MBMustafa Bagriyanik
Mustafa Bagriyanik
GSGurkan Soykan
Gurkan Soykan

9 August 2021 in IEEE Access
Verified
Journal Article
Open access
LKLeyli Karacay
Leyli Karacay
ZBZeki Bilgin
Zeki Bilgin
AGAyse Bilge Gunduz
Ayse Bilge Gunduz
PCPinar Comak
Pinar Comak
ETEmrah Tomur
Emrah Tomur
FKFerhat Karakoc
Ferhat Karakoc
In recent years False Base Stations (FBSs) have received increased attention. A False Base Station can perform active or passive attacks against mobile devices or user equipment (UE) to steal private information, such as International Mobile Subscriber Identifier (IMSI), to trace users locations, or to prevent users from getting service from operators. Most of the existing solutions related to FBS have focused on the detection aspects of the false station rather than locating its position. However, once an FBS is detected in a network, discovering its exact location precisely and remotely becomes highly crucial to initiate preventive actions. In this work, we propose a network-based localization method for estimating the exact geographical position of an FBS whose existence is already detected in a cellular network. Our method relies on a comparative pairwise analysis of the Reference Signals Received Power (RSRP) values reported as a standard procedure by the UEs in the vicinity of FBS through their measurement reports. Specifically, for each pair of related measurement reports, we identify a half-plane indicating the probable location of the FBS and then predict the exact location based on the intersection of all obtained half-planes. We have implemented and experimentally evaluated our proposed method in the Network Simulator 3 ( ns-3 ) and showed that it accurately estimates FBS location with meter-level precision under different scenarios in a cellular network.

16 January 2023 in IEEE Access
Verified
Journal Article
Open access
ESElif Ustundag Soykan
Elif Ustundag Soykan
GSGurkan Soykan
Gurkan Soykan
ETEmrah Tomur
Emrah Tomur
MAMete Akgün
Mete Akgün
The increasing transformation from the legacy power grid to the smart grid brings new opportunities and challenges to the power system operations. Bidirectional communications between home-area devices and the distribution system empower smart grid functionalities. More granular energy consumption data flows through the grid and enables better smart grid applications. This may also lead to privacy violations since the data can be used to infer the consumer’s residential behavior, so-called power signature. Energy utilities mostly aggregate the data especially if the data is shared with stakeholders for the management of market operations. Although this is a privacy-friendly approach, recent works show that this does not fully protect privacy. On the other hand, some applications like nonintrusive load monitoring require disaggregated data. Hence, the challenging problem is to find an efficient way to facilitate smart grid operations without sacrificing privacy. In this paper, we propose a privacy-preserving scheme that leverages consumer privacy without reducing accuracy for smart grid applications like load monitoring. In the proposed scheme, we use a trusted execution environment (TEE) to protect the privacy of the data collected from smart appliances (SAs). The scheme allows customer-oriented smart grid applications as the scheme does not use regular aggregation methods but instead uses customer-oriented aggregation to provide privacy. Hence the accuracy loss stemming from disaggregation is prevented. Our scheme protects the transferred consumption data all the way from SAs to Utility so that possible false data injection attacks on the smart meter that aims to deceive the energy request from the grid are also prevented. We conduct security and game-based privacy analysis under the threat model and provide performance analysis of our implementation. Our results demonstrate that the proposed method overperforms other privacy methods in terms of communication and computation cost. The execution time of aggregation for 10,000 customers that each has 20 SAs is approximately 1 second. The decryption operations performed on the TEE have a linear complexity e.g., 172800 operations take around 1 second while 1728000 operations take around 10 seconds. These results can scale up using cloud or hyper-scalers for real-world applications as our scheme performs offline aggregation.

2 September 2020 in Energies
Verified
Journal Article
Open access
PDF file
ESElif Ustundag Soykan
Elif Ustundag Soykan
MBMustafa Bagriyanik
Mustafa Bagriyanik
Demand response (DR) is a vital element for a reliable and sustainable power grid. Consumer behavior is a key factor in the success of DR programs. In this study, we focus on how consumer reaction to Short Messaging Service (SMS) messages can disturb the demand response. We present a new type of threat to DR programs using SMS phishing attacks. We follow a holistic approach starting from a risk assessment focusing on DR programs’ notification message security following the Smart Grid Information Security (SGIS) risk methodology. We identify threats, conduct impact analysis, and estimate the likelihood of the attacks for various attacker types and motivations. We implemented deterministic and randomized attack scenarios to demonstrate the success of the attack using a state-of-the-art simulator on the IEEE European Low Voltage Feeder Test System. Simulations show that the attack results in local outages, which may lead to large-scale blackouts with the cascading effect on the power system. We conclude that this is a new type of threat that has been overlooked, and it deserves more attention as mobile devices will continually be part of our lives.