According to sources, the French military's computer systems faced significant challenges from the malicious code known as Downadup/Conficker at that time. This malware, first detected in November 2008, exploits vulnerabilities in Windows systems. Downadup/Conficker was capable of dynamically altering its digital signature, effectively evading detection by many antivirus solutions. This worm could also lock out user accounts, seek passwords, block antivirus updates, hinder access to Windows Update, and even spread through the auto-run feature of USB drives. By January 12, 2009, the French Navy's internal network, Intramar, which is responsible for transmitting most digital data, was compromised by this malware. The spread was significant enough that certain operational systems had to be halted.
In response to the infection, the French military took drastic measures. Internet access was severed, and the use of USB drives was temporarily banned. The likely origin of the infection was believed to be direct or indirect web connections, possibly via USB drives or laptops, of "closed networks" – computers meant to be isolated from external access. This incident underlined the difficulties to maintain a large number of Windows assets up to date at that time.