The Cactus Ransomware Group's Attack on Coop

The Cactus ransomware group claims to have attacked Coop. The group threatens to disclose a huge amount of personal information, over 21 thousand directories. Coop is one of the largest retail and grocery providers in Sweden, with approximately 800 stores across the country. The stores are co-owned by 3.5 million members in 29 consumer associations. All surplus that is created in the business goes back to the members or is reinvested in the business, which creates a circular cycle.

Cactus's Operations

Cactus has been in operation since at least March 2023. Cactus has been observed employing known vulnerabilities within VPN appliances to initiate an initial breach. Once gaining entry to the network, Cactus operators engage in activities such as enumerating local and network user accounts and identifying accessible endpoints. They then proceed to generate new user accounts and utilize custom scripts for the automated rollout and activation of the ransomware encryptor through scheduled tasks.

Unique Characteristics of the Ransomware

It is noteworthy that the ransomware encryptor utilized by Cactus exhibits a unique characteristic – it necessitates a decryption key for the execution of the binary, likely implemented to evade detection by anti-virus software. This decryption key is concealed within a file containing random text named ntuser.dat, which is loaded through a scheduled task.