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Rowhammer returns to gaslight your computer – Naked Security

The term “gaslighting” is commonly used to describe individuals who lie to cover up their own wrongdoing while making others doubt their own memory and sanity. This term originated from the 1930s psychological thriller play called Gas Light, where a manipulative husband deceives his wife by pretending to be out while secretly searching for stolen jewels in the apartment above. The husband’s actions cause the gas lights in their home to flicker, thus giving away his criminal activities. Gas lights are connected to a single gas supply, and turning on a burner in one room causes a temporary pressure drop in the entire system, resulting in a noticeable dimming of lights in other rooms. The metaphorical use of “gaslight” in modern language relates to the husband’s attempts to convince his wife that she is going mad, diverting suspicion from his crimes and planning to have her declared insane. However, the tables turn when the wife pretends to help him escape but ultimately ensures his capture by the police.

The concept of gas lights and their behavior under load connects to the cybersecurity challenge of rowhammering. Rowhammering is an electronics problem caused by unwanted interactions within a computer system, similar to the flickering gas lights in the play. In the early days of computers, data storage relied on various methods, such as audio pulses through mercury tubes, magnetic fields in ferrite rings, and electrostatic charges on TV screens. Modern computers use DRAM chips, which consist of nanoscopic capacitors that can store electrical charges to represent binary digits. To read data from a specific capacitor, an entire row of capacitors in the grid must be discharged. Reading the data also erases it, requiring a rewrite to retain the information. Additionally, DRAM capacitors experience data dissipation over time and need regular rewriting to prevent loss.

Rowhammering occurs when writing to a line of capacitors in a DRAM chip affects neighboring capacitors unintentionally. This is similar to the gas light flicker caused by turning on a burner in one room. The more frequently a single line of capacitors is written to, the higher the chance of inducing random bit-flips in nearby memory cells. Interestingly, simply reading from the same block of DRAM memory repeatedly causes it to be rewritten at the same rate, increasing the probability of inducing bit flips. This deliberate manipulation of memory errors is known as rowhammering.

Various cybersecurity attacks have been proposed based on rowhammering, although predicting the side-effects can be challenging. Some attacks require precise control over memory layout, processor setup, and operating system configuration. For example, many processors and operating systems no longer allow unprivileged programs to flush the processor’s memory cache, which prevents repeatedly reading from DRAM capacitors. Additionally, some motherboards allow the DRAM refresh rate to be increased, making it faster than the traditional rate.

In conclusion, the term “gaslighting” originated from the play Gas Light, where a manipulative husband deceives his wife by making her doubt her own sanity. Gas lights in the play flicker, revealing the husband’s criminal activities. This concept relates to the cybersecurity challenge of rowhammering, where writing or reading data in a specific pattern can induce bit-flips in nearby memory cells. Understanding these connections can help in addressing the security implications of rowhammering and developing effective countermeasures.

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