According to the Financial Times, the Iranian government exploited known vulnerabilities in the world's communications infrastructure to locate U.S. military personnel in the run-up to the Iran War and early in the conflict.
Citing research by Mobile Surveillance Monitor and anonymous government officials familiar with espionage, the newspaper reported that the Iranian government had exploited Signaling System 7 (SS7). It is a set of protocols for 2G and 3G networks that has been the backbone of how mobile phone networks connect to each other to route subscribers' calls and text messages around the world.
Intelligence agencies have been exploiting SS7 for years to track mobile phones overseas, and that's what happened in this campaign.
Iran was reportedly able to use this technology to determine the location of U.S. troops stationed at military bases and hotels in Iraq, Bahrain, and other Middle Eastern countries, allowing the Iranian regime to carry out attacks. These attacks left several people injured.
Apart from SS7, Iran also exploited advertising technology used to serve tailored advertisements to mobile phone users. This is another well-known surveillance technique that relies on everyday technology.