It’s the lazy post season so I present you otool-ng. It’s a fork of Apple’s otool with small modifications for things that I use often or dislike in current otool. The segment command LC_MAIN was introduced to replace LC_UNIXTHREAD and one information that is lost is the entrypoint address. While ASLR kind of makes it less useful, I still debug a lot of programs and do other stuff, where ASLR is disabled. [Read More]
Kextstat_ASLR util or how to start hiding your kernel rootkit in Mountain Lion
Welcome back! This is a small post about a quick util that I created yesterday’s night while working on a side project. Mountain Lion introduced kernel ASLR and the kextstat util output doesn’t support (yet?) this feature. The addresses are not the real ones and this is quite annoying (kgmacros from kernel debugging kit also seem to fail at this!). What this util does is to read the kernel extensions information via the /dev/kmem device (hence this util is probably not useful for a large audience) and display it like kextstat does with the correct address for each kext (just the most important information, the linked against info might be added in the future). [Read More]
ExtractMachO: an IDA plugin to extract Mach-O binaries from disassembly
This is an IDA plugin to extract Mach-O binaries located in IDA disassembly, either code or data segments. For now it only supports 32 or 64 isolated binaries and not fat binaries. It also expects a normal formatted binary, not something mangled as my crackme for example. I expect to add support for fat binaries soon. Why did I created this plugin? Everyone is talking about the latest OS X malware, Crisis (or whatever other name everyone is using – AV scene is so lame that no one respects the first name given, blah! [Read More]
How to compile GDB for iOS!
One obstacle that I faced long time ago and came again into spotlight is how to recompile GDB for iOS. It is not useful to fix the ARM disassembler and then not be able to compile. As far as I know there isn’t any documentation available or an easy method to accomplish this – Saurik’s build environment is not public (?) and Apple sources do not compile directly. Darwinbuild project works great for OS X but it’s a question mark for iOS. [Read More]
gdbinit v8.0: simultaneous support for x86/x86_64 and ARM architectures!
Here it is, a merge between the x86 and ARM versions of gdbinit. The only inconvenience is that you need to manually change the target, using the 32bits and 64bits commands for x86/x86_64 architectures, and arm for ARM. That’s a small price to pay for. This version features a lot of cosmetic fixes (indentation mostly) but also some fixes to the ARM related code, and a new command – dumpmacho. This command will dump the Mach-O header to a file. [Read More]
A small improvement to OS X “rootkitery”: bruteforcing sysent discovery, fast & easy!
I love to read about the Human brain and yesterday I was feeling weird about this thing. As far as I know, everyone (publicly) was trying to search sysent in one way or another after Apple removed the sysent symbols but not bruteforcing it. It seems no one bothered to question the original method (Landon Fuller?) and just kept using it. Are there any historical reasons for this? I can’t remember any. [Read More]
A Mac OS X port of Phrack’s CheckIDT util by kad, or another way to retrieve sysent address
This is a OS X port of kad’s checkidt utility featured at Phrack #59. It requires /dev/kmem to be active since task_for_pid on kernel task is prohibited since Snow Leopard. I have added an option to calculate the sysent address via the IDT. The code is not very fail proof because it uses the opcode hex values. Disassembly is probably a better option. This is just a PoC written some time ago so there are some ugly things inside. [Read More]
gdbinit v7.4.4 – the skip command
Here is a small update to gdbinit with a new command, skip. This command will skip over the current instruction, without executing it. Usually I do it manually by set $pc=newvalue but this involves copy & paste and mouse movements and gets boring after a while. It’s great to skip over calls while you are trying some stuff and analysing some program behavior. By default it will not execute the command at the new address. [Read More]
A small update to gdbinit. Many thanks to snare and Plouj for their reports 😃. Here is the changelog: Version 7.4.3 (04/11/2011) – Modified “hexdump” command to support a variable number of lines (optional parameter). – Removed restrictions on type of addresses used in the “dd” command. – Modified the assemble command to support 64bits – You will need to recompile nasm since the version shipped with OS X doesn’t supports 64bits (www. [Read More]
Display Mach-O headers plugin for IDA
This is a simple plugin to display Mach-O headers inside IDA, something I miss from time to time. It was a good excuse to mess a little with IDA SDK. It’s not quite what I had initially in mind but it does the job. I was thinking about something more sophisticated such as allow to display only the segment you wanted and so on. Now I am not sure if it’s worth the effort. [Read More]