SoftICE
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SoftICE is a kernel mode debugger for Microsoft Windows. Crucially, it is designed to run underneath Windows such that the operating system is unaware of its presence. Unlike an application debugger, SoftICE is capable of suspending all operations in Windows when instructed. For driver debugging this is critical due to how hardware is accessed and the kernel of the operating system functions. Because of its low-level capabilities, SoftICE is also popular as a software cracking tool.
Microsoft offers two kernel-mode debuggers, WinDbg and KD, for no charge. However, the full capabilities of WinDbg and KD are available only when two interlinked computers are used. SoftICE therefore is an exceptionally useful tool for difficult driver related development and continues to function well even with Microsoft's latest operating system versions.
Older versions exist for DOS and compatible operating systems. SoftICE was originally produced by a company called NuMega, and was subsequently acquired by Compuware.
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[edit] Naming
"Soft" refers to software, and the "ICE" part of the name is an allusion to in-circuit emulator.
[edit] History
The original SoftICE for DOS was written in 1987 by NuMega founders Frank Grossman and Jim Moskun. The program, written in 80386 assembly language, played the role of an operating system and ran software in virtual 8086 mode. It sold for $386.
SoftICE/W (for Windows) was developed in the 1990 time frame, and was instrumental in the Writing of "Undocumented Windows", by Andrew Schulman, David Maxey and Matt Pietrek. SoftIce/W was derived from an earlier, lesser known product, SoftICE for Netware (32-bit protected mode). One of the key advantages it had over Microsoft's debuggers is that it enabled single machine debugging, rather than requiring a second machine to be connected over a serial port.
The principal developers of SoftICE were Dom Basile ('Mr. SoftICE'), Tom Guinther (Kitchen Sink, Symbol Engine), Gerald Ryckman (Video Drivers and Kitchen Sink), Ray Hsu (Video Drivers W95), and Dan Babcock (SoftICE/NT 3.1/3.5: Universal Video Driver, Symbol Engine), with contributions by a variety of NuMega developers including Frank Grossman, Jim Moskun and Matt Pietrek.
In 1995 the codebase for SoftICE/95 was ported to run on the Windows NT platform.
Newer versions of SoftICE patch deep into Microsoft Windows. As such, old versions of SoftICE are rarely compatible with new versions of Windows. Compuware therefore offers SoftICE as a subscription so that it can be kept up to date and in sync with the latest Microsoft Windows version.
It used to be offered as part of Compuware's DriverStudio package but was discontinued in April 2006.
[edit] Termination
As of April 3, 2006 the DriverStudio product family has been discontinued because of "a variety of technical and business issues as well as general market conditions". Maintenance support was offered until March 31, 2007.
[edit] Anti - SoftICE measures
Probably most of those "technical and business issues" leading to the abandonment of SoftICE have to do with lots of countermeasures software vendors have put in place in order to fend themselves from people employing SoftICE as tool.
These counter measures vary in a wide range. For example here we have a code some vendors used to detect the presence of SoftICE running in the same machine in the early stages of the counter measures tactics:
mov eax, dword ptr [pIDT+2] ; eax -> IDT
add eax, 8 ; eax -> int 1 vector
mov ebx, [eax] ; ebx == int 1 vector
add eax, 16 ; eax -> int 3 vector
mov eax, [eax] ; eax == int 3 vector
and eax, 0ffffh ; strip the selector
and ebx, 0ffffh ; part of it
sub eax, ebx ; find displacement
cmp eax, 10h ;
jne HackedVector ; if it isn't equal then chances are
; SoftICE had tampered with these vectors
These measures have evolved since, not only in quantity but in quality. While most of them can only deter the less experienced and determined hackers, it has become true that SoftICE is no longer a newbie tool of choice. That is certainly a relief for software vendors, who saw in SoftICE their Nemesis.
Today vendor's defenses are based on more sophisticated tools, like ASProtect or PECompact which pack the program code and tamper with entry point addresses so it is hard to find the real program entry point. That is also true for the program DLL's IAT as well.
SoftICE isn't dead yet, but it is more difficult to be used, and that may have led to its discontinuation.
[edit] Alternatives
Both commercial and opensource alternatives exist for the SoftICE.
[edit] Commercial Alternatives
Syser Debugger aims to be a comprehensive replacement for SoftICE, running on 32-bit versions of Windows Vista/XP/2003/2000, including SMP, HyperThreading and multi-core CPUs.
[edit] Open Source Alternatives
An open source kernel debugger similar to SoftICE named Rasta Ring 0 Debugger is available on the project page. It provides low level debugging for Microsoft Windows, Linux, OpenBSD, NetBSD, and FreeBSD.
