18 August 2020 by Phillip Johnston • Last updated 15 August 2023Researchers at Eclypsium discovered a major security flaw in the widely used GRUB2 bootloader, which is used on Windows and Linux devices. The vulnerability, dubbed “BootHole”, is triggered by a buffer overflow during the parsing of the grub.cfg file. Modifying this file does not alter the integrity of the signed vendor shim or GRUB2 bootloader executables. An attacker with administrator privileges can modify the grub.cfg file to trigger the overflow without being detected. Impact This vulnerability gives an attacker “virtually unlimited control over the victim device”. Most notably, it …
Continue reading “BootHole: Bypass Secure Boot in GRUB2”
For most programmers, a C or C++ program’s life begins at the main function. They are blissfully unaware of the hidden steps that happen between invoking a program and executing main. Depending on the program and the compiler, there are all kinds of interesting functions that get run before main, automatically inserted by the compiler and linker and invisible …
Continue reading "Exploring Startup Implementations: OS X"
For most programmers, a C or C++ program’s life begins at the main function. They are blissfully unaware of the hidden steps that happen between invoking a program and executing main. Depending on the program and the compiler, there are all kinds of interesting functions that get run before main, automatically inserted by the compiler …
Continue reading "Exploring Startup Implementations: Newlib (ARM)"
For most programmers, a C or C++ program’s life begins at the main function. They are blissfully unaware of the hidden steps that happen between invoking a program and executing main. Depending on the program and the compiler, there are all kinds of interesting functions that get run before main, automatically inserted by the compiler …
Continue reading "A General Overview of What Happens Before main()"
