ARM_12-bit_Immediates_are_Too_High_Level
Encoding 12 bit immediate values for 32 bit ARM instructions can get somewhat complicated when the numbers get large enough, click this article for more details.
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Invoke_is_Too_High_Level
Invoke is a common calling convention for assembly source, especially as found as examples on the internet. But 'invoke' isn't assembly, it's abstracted, and it makes disassembly harder to follow. This post is a discussion of this issue and how I came to using the standard assembly 'call' convention.
ARM_Assembly_is_Too_High_Level_-_ROR_and_RRX
RRX is encoded as ROR with the imm5 field hardcoded as 0's.
ARM_Assembly_is_Too_High_Level_-_Moving_by_Shifting
The MOV and shift instructions (like LSL) are encoded the same. You could use the LSL instruction with the imm5 field hardcoded to 0's and it will encode exactly the same as MOV.
sed-regex_Based_BrainFuck_Compiler
Building a BrainFuck compiler with the main component being the sed tool.
Assembly_is_Too_High_Level_-_Commutative_Property,_Sometimes_-_it_may_save_your_byte
The order of adding two registers in a pointer shouldn't matter logically, but it does when it comes to encoding. This is because the 2nd register is a multiplier even if only be 1. Read more for the interesting details.
Assembly_is_Too_High-Level_-_Signed_Displacements
An exploration of some ambiguities that signed numbers can introduce to your assembler, what your assembler will choose, and how you can choose anything you want.
Boot_Sector_Graphical_Programming_-_Tutorial
A quickstart guide to making some boot sector games. This guide assumes you know some x86 basics. From there, you learn how to boot a skeleton with a stack, video memory, keyboard control, timing loops, colors, and random.
CactusCon_Slides_-_Machining_-_A_Love_Story
These are the slides (with slide notes) that I gave at Cactus Con in 2016. It's about my unrealized childhood dream of programming in machine code directly (unrealized as a child).
Assembly_is_Too_High_Level_-_Repetition_of_REP_Instructions_That_Don't_Repeat_Anything
Abuse of the REP prefix for instructions that it doesn't apply to.
Assembly_is_Too_High_Level_-_Why_ESP_doesn't_scale_-_But_EBP_can_still_Base
Not all registers can be scaled (multiplied by 1, 2, 4, & 8), read on for details of why this is a thing due to machine encoding.
Assembly_is_Too_High_Level_-_Redundant_Bit_commands
Some insctructions have the operand of immediate 1 hardcoded, but you can still use 1 as an operand value for the variale immediate data.
Assembly_is_Too_High_Level_-_SIB_Doubles
Some abuse and redundancy discussion involving scaling by 2 and other edge cases with the SIB table.
Assembly_is_Too_High_Level_-_Load_InEffective_Address
LEA is encoded with the MODR/M byte, even though that would allow for some invalid encodings. Read on if you want to explore what happens when we do this.
Assembly_is_Too_High-Level_-_TEST_r32,_r-m32,_exists_in_assembly,_but_not_the_machine
A test instruction that is valid in assembly language, but has no machine encoding. The assembler uses something logically equivalent when encoded.
Assembly_is_Too_High-Level_-_BSWAPin_16-bit_Registers
It is invalid assembly to BSWAP 16-bit registers, read on to find out what happens when we try to do it anyway.
Assembly_is_Too_High-Level_-_Self_Modifying_Code_with_Basic_Arithmetic
Use simple math instructions to modify other instructions for some fun self modifying code.
Follow-up_on_creating_Vm0wd2Qy_-_9000
There were some questions to my methods for the original post on Vm0wd2Qy, so this is a follow-up to explain everything.
Assembly_is_Too_High_Level_-_Jump_Near_When_Short
Encoding of the JMP instruction can have reduncancies, here we explore using less common encodings.
Vm0wd2Qy
Some recursive Base64 magic.
Assembly_is_Too_High_Level_-_Subtracting_by_Comparing_-_Propeller
SUB and CMP are already similar enough in x86, but in Propeller, they are even encoded super similar, to where you can do some stupid assembly syntax to convert one into the other.
Assembly_is_Too_High-Level_-_AAD-AAM,_Even_the_Math_is_Too_High-Level
This is by far my favorite x86 encoding thing; you can unlock way more functionality with this instruction that requires machine encoding beyond just basic assembly.
Assembly_is_Too_High_Level_-_Propeller_NOPs,_like_if_never
Pretty much any insctruction can be a NOP, due to a 'never' condition. ARM is very similar in this way.
Obscure_FISTing
Using the FIST instruction as an obfuscation technique, because fisting.
Assembly_Is_Too_High_Level_-_Undocumented_Code_Exploration
Taking a look at some blank spots in the Intel manuals opcode map.
Assembly_Is_Too_High-Level_-_Full_Offsets
Intel tries to abuse the ModR/M table for variable byte NOPs, read on to see how we can do some better abuse for multibyte NOPs that are also still sledable.
Assembly_Is_Too_High-Level_-_OP_REG,imm_redundancies
Some instructions have a register (a common one like EAX) hardcoded, but you can still use the non hardcoded encoding and still pick EAX. This offers a redundancy.
Assembly_Is_Too_High-Level_-_Better_Call_SAL
SAL is valid assembly, but gets encoded as SHL, yet we can still hardcode the real SAL, and it works as it should!
How_to_Machine
A tutorial/walkthrough on some of my methods of writing code in machine code instead of assembly language.
Bass_+_Computer
A breif description of the brain I put into my bass guitar.
Assembly_Is_Too_High-Level_-_Consistent_Instruction_Sizes
An abuse of prefixes to get every instruction on a program to be encoded with the same amount of bytes.
8ball_can_now_speedball
An announcment that the 8ball tool now supports regular expression denial of service.
Assembly_Is_Too_High-Level_-_Shell_with_178_ADDs_and_1_JMP
An obfuscation technique that spotlights the ADD instruction.
I_GOTO
Partly a troll, but also I couldn't thing of a better way to solve a problem then to use a GOTO at the time I coded this.
2K_of_RAM
A lab that I was never assigned. This tought me the lesson of how much you can do when not given the bias that it is supposed to be hard. In this case, tedious.
Unimpressive_Presentation_Software
An announcment of my slidedeck software.
Assembly_Is_Too_High-Level_-_Fences
Shows that there are many other encodings to the several FENSE instructions.
Assembly_Is_Too_High-Level_-_Redundant_Machine-Code_-_Adventures_of_ModR-M,_SIB,_and_REX
MoDR/M and SIB tables can get pretty heavy with redundancies, read on to dive into it.
'One_or_more'_is_ambiguous_-_The_limit_of_the_'+'_regex_metacharacter
The plus character isn't actually handled as 1 or more, the upper limmit is usually capped at somepoint. Read on to see how one implementation caps the upper limit.
Regex_Is_Too_High_Level_-_Equivalent_Quantifiers
There are different syntactical choises for quantifiers when using regex, but you only really need one of them.
RE_TLDR
A cheat sheet for common regex syntax.
Unused_8ball_Art
This art was supposed to go into a HOPE and DEF CON talk, but didn't make it into the deck. Read on to hear more about it.
Assembly_Is_Too_High-Level_-_Redundant_Mnemonics
The most boring of x86 redundancies; redundant mnemonics.
Assembly_Is_Too_High-Level_-_Branch_Hints
This was one of the first x86 oddities that I chased, it wasn't super interesting, but it's what got me started going down this deep dark path.
I'm_using_WordPress
First blog post in original WordPress blog format