Category Archives: Security

Valgrind trapdoor and fun

Valgrind has a client request mechanism, which allows a client to pass some information back to valgrind. This includes asks valgrind to do a logging in its own environment, tells valgrind a range of VA being used as a new … Continue reading

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Some notes on SGX OwnerEpoch and Sealing

Intel SGX has been there in the market for while. Yet there are still a lot of misundrestandings and mysteries about this technology. This post provides an introduction to Intel SGX OwnerEpoch and Sealing, discusses their security impacts, and speculates … Continue reading

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Rowhammer Pine64

Rowhammer attacks have been well known, and gotten a lot of publications already. However, we notice that most rowhammers happened on x86 architecture due to the easy access to clflush from the user space. ARM architecture (both ARMv7 and ARMv8) … Continue reading

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Running Multics on Linux (Fedora 27)

This post follows the “Multics Simulator Instructions”[1] (with some tweaks) to setup Multics simulator dps8m and run Multics on my Fedora 27. Other Linux distro (Ubuntu/Debian/Raspbian) may need some changes but basically work the same way. Experience the cutting-edge secure … Continue reading

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Some notes on the Monotonic Counter in Intel SGX and ME

SGX sealing is vulnerable to rollback attacks as the enclave is not able to tell if the sealed data is the latest or a old copy. To mitigate this attack, monotonic counter (MC) has been introduced in Intel SGX SDK … Continue reading

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A PoC of DoS attack in Elixir Actor Model

The naive way of using the Actor model in Elixir is using “receive” in a loop, which is then “spawn”d as a Erlang process. Unfortunately, a potential DoS attack could happen if the pattern matching is not coded carefully with … Continue reading

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Understanding kcov – play with -fsanitize-coverage=trace-pc from the user space

kcov is a kernel feature used to support syzkaller[1]. To provide the code coverage information from the kernel itself, the GCC compiler was patched to instrument the kernel image[2]. The kernel itself was also patched to enable this feature where … Continue reading

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