Password Cracking Methods and Techniques in Computer Forensic Investigation

Öz

The unending increase in information systems and data use has triggered the birth of danger to information security. According to recently published reports, apart from military forces and e-commerce websites, ordinary users have begun to use encryption techniques to protect systems and documents. In spite of precautions, smart attacks prepared using a variety of concealing techniques overcome available protection methods and can obtain the passwords and user names of on the target system. Corporate firms and ordinary users commonly use new-generation encryption methods to hide their data. This situation creates large obstacles forto the investigation of computer systems and files which are the subject of forensic events, especially. If a suspect uses a computer system with encrypted files, to obtain evidence, firstly, it is necessary to know these encryptions or to crack them. In this step, if the suspect does not give law enforcement the encryptions willingly, forensic experts attempt to break the encryption with a variety of methods. This process is generally difficult, and in some situations, the encrypted data on the suspect’s system cannot be reached. This study provides two contributions. The first is that a detailed investigation of the most commonly used encryption cracking methods are investigated in detail. Secondly, an example forensic case encrypted with the “BitLocker” data encryption method is investigated and the steps to break the encrypted data are investigated. The results

Anahtar Kelimeler

• Password Cracking
• Data Encryption
• Security Attacks
• Analysis Methods

Adli Bilişim İncelemelerinde Şifre Kırma Yöntem ve Teknikleri

Öz

Bilgi sistemleri ve veri kullanımındaki sonsuz artış, bilgi güvenliğinde tehlikenin doğuşunu tetikledi. Son yayınlanan raporlara göre askeri kuvvetler ve e-ticaret web siteleri dışında sıradan kullanıcılarda sistemleri ve belgelerini korumak için şifreleme teknikleri kullanmaya başlanmışlardır. Alınana tedbirlere rağmen çeşitli gizleme tekniklerini kullanarak hazırlanan akıllı saldırılar mevcut korunma yöntemlerini atlatarak hedef sistemdeki parola ve kullanıcı adlarını ele geçirebilmektedir. Kurumsal firmalar ve sıradan kullanıcılar verilerini gizlemek için yeni nesil şifreleme yöntemlerini yaygın olarak kullanmaktadır. Bu durum özellikle adli olaylara konu olan bilgi sistemleri ve dosyaların incelenmesinde büyük engeller oluşturmaktadır. Eğer şüpheli kişi kullanmış olduğu bilgi sistemi veya dosyalarını şifrelenmiş ise delil elde etmek için önce bu şifrelerin önceden bilinmesi ya da şifrenin kırılması gereklidir. Bu adımda şüpheli kendi rızasıyla parola kolluk kuvvetlerine vermemesi durumunda adli uzmanlar çeşitli yönetmelerle şifreleri kırmaya çalışmakta bu süreç genellikle zor olmakta ve bazı durumlarda şüpheli sistemdeki şifreli verilere ulaşılamamaktadır. Bu çalışma iki katkı sunmaktadır. İlk olarak en çok kullanılan şifre kırma yöntemleri detaylı olarak incelenmiştir. İkincisi, “BitLocker” veri şifreleme yöntemiyle şifrelenmiş örnek bir adli vaka incelenerek şifreli verileri kırılma adımları incelenmiştir. Sonuçlardan şifrelenmiş verilerin erişmek için kullanılan yöntemin etkili olduğunu ve şifrelerin kırıldığı göstermektedir.

Anahtar Kelimeler

• Şifre Kırma
• Veri Şifreleme
• Güvenlik Saldırıları
• Analiz Yöntemleri

Kaynakça

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