Security experts believe that the NotPetya attack originated from an update of M.E.Doc, a Ukrainian tax accounting package developed by Intellect Service. and
Mikko Hyppönen, a security expert at
F-Secure, described it as a primary accounting software for many Ukrainian firms. A similar incident occurred on 18 May 2017, when the XData ransomware spread through a compromised update of M.E.Doc. Hundreds of accounting departments were affected in Ukraine. The cyberattack involved malware that resembled
Petya ransomware but was later found to function as a wiper rather than traditional ransomware. Like the
WannaCry ransomware attack in May 2017, NotPetya used the
EternalBlue exploit, which targeted a vulnerability in older versions of the
Microsoft Windows operating system. When executed, NotPetya encrypted the
master boot record (MBR), preventing the operating system from loading. It then displayed a message demanding USD 300 in
Bitcoin, but researchers found that data recovery was not possible. The software also spread within networks by exploiting the
Server Message Block (SMB) protocol in Windows. Additionally, NotPetya incorporated
Mimikatz, a proof-of-concept tool created in 2011 to demonstrate how Windows stored passwords in memory. Attackers used it to extract credentials, escalate privileges, and move laterally across networked systems. Security expert
Lesley Carhart stated, "Every method of exploitation that the attack used to spread was preventable by well-documented means." Security experts determined that the variant of Petya used in the 2017 Ukraine cyberattacks had been modified and was subsequently named NotPetya or Nyetna to distinguish it from the original ransomware. NotPetya encrypted entire files, not just the Master File Table (MFT), and in some cases, functioned as a wiper, permanently destroying or irreversibly altering data, with no known method of recovery. Some security experts saw that the software could intercept passwords and perform administrator-level actions that could further ruin computer files. They also noted that the software could identify specific computer systems and bypass infection of those systems, suggesting the attack was more surgical in its goal. According to Nicholas Weaver of the
University of California the hackers had previously compromised M.E.Doc "made it into a remote-control Trojan, and then they were willing to burn this asset to launch this attack." == Attack ==