New Delhi: Nepal Telecom has been subjected to a terrible "cyber attack" from China. Chinese hackers have attacked Nepal Telecom and stolen the call details of all Nepali users. By hacking the Oracle Glass Fish Server used by the telecom company, the Chinese hackers have stolen all the call details of Nepalis. According to technical experts, the hackers used 41 Tactics of Advanced Persistent Threat (APT) and 71 Tactics of Advanced Persistent Threat (APT) and backdoor weapons. Hackers have been seen taking CDR data from telecom servers to APT 41 and APT 71. It has also been found that the data stolen from the telecom server has been kept on the dark web for sale. The CDR call data record of the telco was put for selling on June 29. Nepal Telecom has shut down its server to subdue the higher threat, several local media reports. NTC spokesman Rajesh Joshi said: "We have not deciphered the identity of the hackers. We switched off the server to save our data after we received information of a possible interference into our server." Apparently, Chinese hackers gained access to Oracle GlassFish Server operated by NTC and collected Call Data Records (CDR). However, the telco claims its call data are safe, NepaliTelecom.com said. NTC Managing Director Dilli Ram Adhikari says the company's main server is secure. Speaking to reputed outlets, he said: "Hackers might have breached into a dated server of CDMA. The company's team of expert technicians are looking into the matter to trace the culprits. Our main server is protected by a highly secure firewall and remains safe." NepaliTelecom.com said China has often well-guarded the company on a state level which has encouraged them to launch attacks on foreign companies over the years. This led to believe that the Chinese may have been behind this attack on NTC. The infamous Tag-22 has hacked and even put on sale telecom-related data belonging to countries such as Taiwan and the Philippines. The report said China has often incurred the wrath of foreign states for a supposedly encouraging state-level breach which it has categorically denied. For now, there is no proof that the Chinese group was behind the group but the leads hint there. Hacking into telecom means a huge swatch of user data would be vulnerable for sinister use. NTC will have to be more cautious in the coming days to protect user data in the future.