Thursday, August 17, 2017

Obfuscated String/Shellcode Generator - Online Tool



String Shellcode |

Shellcode will be cleaned of non-hex bytes using the following algorithm:

s = s.replace(/(0x|0X)/g, "");
s = s.replace(/[^A-Fa-f0-9]/g, "");

See also: Overflow Exploit Pattern Generator - Online Tool.

About this tool

I'm preparing a malware reverse engineering class and building some crackmes for the CTF. I needed to encrypt/obfuscate flags so that they don't just show up with a strings tool. Sure you can crib the assembly and rig this out pretty easily, but the point of these challenges is to instead solve them through behavioral analysis rather than initial assessment. I'm sure this tool will also be good for getting some dirty strings past AV.

Sadly, I'm still not satisfied with the state of C++17 template magic for compile-time string obfuscation or I wouldn't have had to make this. I remember a website that used to do this similar thing for free but at some point it moved to a pay model. I think maybe it had a few extra features?

This instruments pretty nicely though in that an ADD won't be immediately followed by a SUB, which is basically a NOP. Same with XOR, SHIFT, etc. It can also MORPH the output even more by using the current string iteration in the arithmetic to add entropy.

Only ASCII/ANSI is supported because if there's one thing I dislike more than JavaScript it's working with UCS2-LE encodings. And the only language it generates is raw C/C++ because those are the languages you would most likely need something like this for. Post a comment if there's a bug, and feel free to rip the code out if you want to.

Saturday, July 1, 2017

Puppet Strings - Dirty Secret for Windows Ring 0 Code Execution

Update July 3, 2017: FuzzySec has also previously written some info about this.

Ever since I began reverse engineering Shadow Brokers dumps [1] [2] [3], I've gotten into the habit of codenaming my projects. This trick is called Puppet Strings , and it lets you hitch a free ride into Ring 0 (kernel mode) on Windows.

Some nation-state malware, such as Backdoor.Remsec by the ProjectSauron/Strider APT and Trojan.Turla by the Turla APT, performs a similar operation. However, the traditional nation-state modus operandi involves 0-day exploitation.

But why waste 0-days when you can use kn0wn-days?

Premise

  1. If you're running as an elevated admin, you're allowed to load (signed) drivers.
    • Local users are almost always admins.
    • UAC is known to be fundamentally broken.
  2. Load any (signed) driver with a kn0wn code execution vulnerability and exploit it.
    • It's a fairly obvious idea, and elementary to perform.
    • Windows does not have robust certificate revocation.
      • Thus, the DSE trust model is fundamentally broken!

Ordinarily, Ring 0 is forbidden unless you have an approved Extended Validation (EV) Code-Signing Certificate (out of reach for most, especially for malicious purposes). There is a "Driver Signature Enforcement" (DSE) security feature present in all modern 64-bit versions of Windows.

This enforcement can only be "officially" bypassed in two ways: attaching a kernel debugger or configuration at the advanced boot options menu. While these are common procedures for driver developers, they are highly-atypical actions for the average user.

That's right, I'm talking about simply loading high-profile vulnerable drivers like capcom.sys:

Originally introduced in September 2016 as a form of video game anti-cheat, it was quickly discovered that the capcom.sys driver has an ioctl which disables Supervisor Mode Execution Prevention (SMEP) and executes a provided Ring 3 (user mode) function pointer with Ring 0 privileges. It's even kind enough to pass you a function pointer to MmGetSystemRoutineAddress(), which is basically like GetProcAddress() but for ntoskrnl.exe exports.

The unfortunate part is it can still be easily loaded and exploited to this day.

If a driver is signed with a valid timestamp, it also doesn't matter if the certificate has expired, as long as it isn't revoked. This trick is only possible because the Microsoft and root CA mechanisms for revoking driver signatures seems bad. This halfhearted approach violates the trust model that public key infrastructure is supposed to be built upon, as defined in the X.509 standard. Perhaps like UAC it is not a security boundary?

Capcom.sys has been around for almost a year, and is easily one of the most well-known and simplest driver exploits of all time.

While this driver is flagged 15/61 on VirusTotal, I have a personal list of known-vulnerable drivers that are 0/61 detection. They aren't too hard to find if you keep your eyes open to netsec news.

Proof of Concept

Code is available on GitHub at zerosum0x0/puppetstrings. To run it, you will need to independently obtain the capcom.sys driver (I don't want to deal with weird licensing issues).

Test system was Windows 10 x64 Redstone 3 (Insider pre-release), just to show the new Driver Signing Policies (and its list of exceptions) introduced in Redstone 1 do not address this issue. This works on all versions of Windows if you update the EPROCESS.ActiveProcessLinks offset.

1: kd> dt !_EPROCESS ActiveProcessLinks
   +0x2e8 ActiveProcessLinks : _LIST_ENTRY

For the PoC, I had to do something relatively malicious to get the point across. Getting to Ring 0 with this technique is simple, doing something interesting once there is more difficult (e.g. we can already load drivers, the usual SYSTEM shell can be obtained through less dangerous methods).

I load capcom.sys, pass it a function which performs the old rootkit technique of unlinking the current process from the EPROCESS.ActiveProcessLinks circularly-linked list, and then unload capcom.sys. This methodology is instant and makes the current process not show up in user mode tools like tasklist.exe.

static void rootkit_unlink(PEPROCESS pProcess)
{
 static const DWORD WIN10_RS3_OFFSET = 0x2e8;

 PLIST_ENTRY plist = 
  (PLIST_ENTRY)((LPBYTE)pProcess + WIN10_RS3_OFFSET);

 *((DWORD64*)plist->Blink) = (DWORD64)plist->Flink;
 *((DWORD64*)plist->Flink + 1) = (DWORD64)plist->Blink;

 plist->Flink = (PLIST_ENTRY) &(plist->Flink);
 plist->Blink = (PLIST_ENTRY) &(plist->Flink);
}

Of course, doing this in a modern rootkit is foolish, as PatchGuard has at least 4 different process list checks (CRITICAL_STRUCTURE_CORRUPTION Bug Check Arg4 = 4, 5, 1A, and 1B). But you can get experimental and think of something else cool to do, as you enjoy all of the freedoms Ring 0 brings.

DOUBLEPULSAR showed us there's a lot of creative ideas to run in the kernel, even outside of a driver context. DSEFix exploits the same vulnerable VirtualBox driver used by Trojan.Turla to disable Driver Signature Enforcement entirely. It's even possible to use some undocumented features to create a reflectively-loaded driver, if one were so inclined...

If you want to learn more about techniques like this, come to the Advanced Windows Post-Exploitation / Malware Forward Engineering DEF CON 25 workshop.

ThreadContinue - Reflective DLL Injection Using SetThreadContext() and NtContinue()

In the attempt to evade AV, attackers go to great lengths to avoid the common reflective injection code execution function, CreateRemoteThread(). Alternative techniques include native API (ntdll) thread creation and user APCs (necessary for SysWow64->x64), etc.

This technique uses SetThreadContext() to change a selected thread's registers, and performs a restoration process with NtContinue(). This means the hijacked thread can keep doing whatever it was doing, which may be a critical function of the injected application.

You'll notice the PoC (x64 only, #lazy) is using the common VirtualAllocEx() and WriteVirtualMemory() functions. But instead of creating a new remote thread, we piggyback off of an existing one, and restore the original context when we're done with it. This can be done locally (current process) and remotely (target process).

Stage 0: Thread Hijack

Code can be found in hijack/hijack.c

  1. Select a target PID.
  2. Process is opened, and any thread is found.
  3. Thread is suspended, and thread context (CPU registers) copied.
  4. Memory allocated in remote process for reflective DLL.
  5. Memory allocated in remote process for thread context.
  6. Set the thread context stack pointer to a lower address.
  7. Change thread context with SetThreadContext().
  8. Resume the thread execution.

Stage 1: Reflective Restore

Code can be found in dll/ReflectiveDll.c

  1. Normal reflective DLL injection takes place.
  2. Optional: Spawn new thread locally for a primary payload.
  3. Optional: Thread is restored with NtContinue(), using the passed-in previous context.

You can go from x64->SysWow64 using Wow64SetThreadContext(), but not the other way around. I unfortunately did not observe possible sorcery for SysWow64->x64.

One major hiccup to overcome, in x64 mode, is that the register RCX (function param 1) is volatile even across a SetThreadContext() call. To overcome this, I stored a cave (in this case, the DOS header). Luckily, NtContinue() allows setting the volatile registers, so there's no issues in the restoration process, otherwise it would have needed a hacky code cave inserted or something.

    // retrieve CONTEXT from DOS header cave
    lpParameter = (LPVOID)*((PULONG_PTR)((LPBYTE)uiLibraryAddress+2));

Another issue is we could corrupt the original threads stack. I subtracted 0x2000 from RSP to find a new spot to spam up.

I've seen similar (but non-successful) techniques for code injection. I found a rare amount of similar information [1] [2]. These techniques were not interested in performing proper cleanup of the stolen thread, which is not practical in many circumstances. This is essentially the same process that RtlRemoteCall() follows. As such, there may be issues for threads in a wait state returning an incorrect status? None of these sources uses reflective restoration.

As user mode API is highly explored territory, this may not be an original technique. If so, take the example for what it is ([relatively] clean code with academic explanation) and chalk it up to multiple discovery. Leave flames, spam, and questions in the comments!

If you want to learn more about techniques like this, come to the Advanced Windows Post-Exploitation / Malware Forward Engineering DEF CON 25 workshop.

Proposed Windows 10 EAF/EMET "Bypass" for Reflective DLL Injection

Windows 10 Redstone 3 (Fall Creator's Update) is adding Exploit Guard, bringing EMET's Export Address Table Access Filtering (EAF) mitigation, among others, to the system. We are still living in a golden era of Windows exploitation and post-exploitation, compared to the way things will be once the world moves onto Windows 10. This is a mitigation that will need to be bypassed sooner or later.

EAF sets hardware breakpoints that check for legitimate access when the function exports of KERNEL32.DLL and NTDLL.DLL are read. It does this by checking if the offending caller code is part of a legitimately loaded module (which reflective DLL injection is not). EAF+ adds another breakpoint for KERNELBASE.DLL. One bypass was searching a DLL such as USER32.DLL for its imports, however Windows 10 will also be adding the brand new Import Address Table Access Filtering (IAF).

So how can we avoid the EAF exploit mitigation? Simple, reflective DLLs, just like normal DLLs, take an LPVOID lpParam. Currently, the loader code does nothing with this besides forwarding it to DllMain. We can allocate and pass a pointer to this struct.

#pragma pack(1)
typedef struct _REFLECTIVE_LOADER_INFO
{

    LPVOID  lpRealParam;
    LPVOID  lpDosHeader;
    FARPROC fLoadLibraryA;
    FARPROC fGetProcAddress;
    FARPROC fVirtualAlloc;
    FARPROC fNtFlushInstructionCache;
    FARPROC fVirtualLock;

} REFLECTIVE_LOADER_INFO, *PREFLECTIVE_LOADER_INFO;

Instead of performing two allocations, we could also shove this information in a code cave at start of the ReflectiveLoader(), or in the DOS headers. I don't think DOS headers are viable for Metasploit, which inserts shellcode there (that does some MSF setup and jumps to ReflectiveLoader(), so you can start execution at offset 0), but perhaps in the stub between the DOS->e_lfanew field and the NT headers.

Reflective DLLs search backwards in memory for their base MZ DOS header address, requiring a second function with the _ReturnAddress() intrinsic. We know this information and can avoid the entire process (note: method not possible if we shove in DOS headers).

Likewise, the addresses for the APIs we need are also known information before the reflective loader is called. While it's true that there is full ASLR for most loaded DLL modules these days, KERNEL32.DLL and NTDLL.DLL are only randomized upon system boot. Unless we do something weird, the addresses we see in the injecting process will be the same as in the injected process.

In order to get code execution to the point of being able to inject code in another process, you need to be inside of a valid context or previously have necessary function pointers anyways. Since EAF does not alert from a valid context, obtaining pointers in the first place should not be an issue. From there, chaining this method with migration is not a problem.

This kind of removes some of the novelty from reflective DLL injection. It's known that instead of self-loading, it's possible to perform the loader code from the injector (this method is seen in powerkatz.dll [PowerShell Empire's Mimikatz] and process hollowing). However, recently there was a circumstance where I was forced to use reflective injection due to the constraints I was working within. More on that at a later time, but reflective DLL injection, even with this extra step, still has plenty of uses and is highly coupled to the tools we're currently using... This is a simple fix when the issue comes up.

Wednesday, June 7, 2017

Talk/Workshop at DEF CON 25

Just got the word that @aleph___naught and I will be presenting a talk and workshop at DEF CON 25.

Our talk is a post-exploitation RAT using the Windows Script Host. Executing completely from memory with tons of ways to fork to shellcode. Will contain some original research (with the help of @JennaMagius and @The_Naterz) and amazing prior work by @tiraniddo, @subTee, and @enigma0x3. Queue @mattifestation interjecting with something about app whitelisting!

The workshop is not just the tactics, but the code and reverse engineering behind all the stuff in penetration testing rootkits such as Meterpreter and PowerShell Empire. It will include a deep look into Windows internals and some new concepts and ideas not yet present in the normal set of tools.

All slides and code will be posted at the end of DEF CON.

ETERNALBLUE: Exploit Analysis and Port to Microsoft Windows 10

The whitepaper for the research done on ETERNALBLUE by @JennaMagius and I has been completed.

Be sure to check the bibliography for other great writeups of the pool grooming and overflow process. This paper breaks some new ground by explaining the execution chain after the memory corrupting overwrite is complete.

PDF Download

Errata

r5hjrtgher pointed out the vulnerable code section did not appear accurate. Upon further investigation, we discovered this was correct. The confusion was because unlike the version of Windows Server 2008 we originally reversed, on Windows 10 the Srv!SrvOs2FeaListSizeToNt function was inlined inside Srv!SrvOs2FeaListToNt. We saw a similar code path and hastily concluded it was the vulnerable one. Narrowing the exact location was not necessary to port the exploit.

Here is the correct vulnerable code path for Windows 10 version 1511:

How the vulnerability was patched with MS17-010:

The 16-bit registers were replaced with 32-bit versions, to prevent the mathematical miscalculation leading to buffer overflow.

Minor note: there was also extra assembly and mitigations added in the code paths leading to this.

To all the foreign intelligence agencies trying to spear phish I've already deleted all my data! :tinfoil:

Friday, April 21, 2017

DoublePulsar Initial SMB Backdoor Ring 0 Shellcode Analysis

One week ago today, the Shadow Brokers (an unknown hacking entity) leaked the Equation Group's (NSA) FuzzBunch software, an exploitation framework similar to Metasploit. In the framework were several unauthenticated, remote exploits for Windows (such as the exploits codenamed EternalBlue, EternalRomance, and EternalSynergy). Many of the vulnerabilities that are exploited were fixed in MS17-010, perhaps the most critical Windows patch in almost a decade.

Side note: You can use my MS17-010 Metasploit auxiliary module to scan your networks for systems missing this patch (uncredentialed and non-intrusive). If a missing patch is found, it will also check for an existing DoublePulsar infection.

Introduction

For those unfamiliar, DoublePulsar is the primary payload used in SMB and RDP exploits in FuzzBunch. Analysis was performed using the EternalBlue SMBv1/SMBv2 exploit against Windows Server 2008 R2 SP1 x64.

The shellcode, in tl;dr fashion, essentially performs the following:

  • Step 0: Shellcode sorcery to determine if x86 or x64, and branches as such.
  • Step 1: Locates the IDT from the KPCR, and traverses backwards from the first interrupt handler to find ntoskrnl.exe base address (DOS MZ header).
  • Step 2: Reads ntoskrnl.exe's exports directory, and uses hashes (similar to usermode shellcode) to find ExAllocPool/ExFreePool/ZwQuerySystemInformation functions.
  • Step 3: Invokes ZwQuerySystemInformation() with the enum value SystemQueryModuleInformation, which loads a list of all drivers. It uses this to locate Srv.sys, an SMB driver.
  • Step 4: Switches the SrvTransactionNotImplemented() function pointer located at SrvTransaction2DispatchTable[14] to its own hook function.
  • Step 5: With secondary DoublePulsar payloads (such as inject DLL), the hook function sees if you "knock" correctly and allocates an executable buffer to run your raw shellcode. All other requests are forwarded directly to the original SrvTransactionNotImplemented() function. "Burning" DoublePulsar doesn't completely erase the hook function from memory, just makes it dormant.

After exploitation, you can see the missing symbol in the SrvTransaction2DispatchTable. There are supposed to be 2 handlers here with the SrvTransactionNotImplemented symbol. This is the DoublePulsar backdoor (array index 14):

Honestly, you don't usually wake up in the morning and feel like spending time dissecting ~3600 some odd bytes of Ring-0 shellcode, but I felt productive today. Also I was really curious about this payload and didn't see many details about it outside of Countercept's analysis of the DLL injection code. But I was interested in how the initial SMB backdoor is installed, which is what this post is about.

Zach Harding, Dylan Davis, and I kind of rushed through it in a few hours in our red team lab at RiskSense. There is some interesting setup in the EternalBlue exploit with the IA32_LSTAR syscall MSR (0xc000082) and a region of the Srv.sys containing FEFEs, but I will instead focus on just the raw DoublePulsar methodology... Much like the EXTRABACON shellcode, this one is crafty and does not simply spawn a shell.

Detailed Shellcode Analysis

Inside the Shadow Brokers dump you can find DoublePulsar.exe and EternalBlue.exe. When you use DoublePulsar in FuzzBunch, there is an option to spit its shellcode out to a file. We found out this is a red herring, and that the EternalBlue.exe contained its own payload.

Step 0: Determine CPU Architecture

The main payload is quite large because it contains shellcode for both x86 and x64. The first few bytes use opcode trickery to branch to the correct architecture (see my previous article on assembly architecture detection).

Here is how x86 sees the first few bytes.

You'll notice that inc eax means the je (jump equal/zero) instruction is not taken. What follows is a call and a pop, which is to get the current instruction pointer.

And here is how x64 sees it:

The inc eax byte is instead the REX preamble for a NOP. So the zero flag is still set from the xor eax, eax operation. Since x64 has RIP-relative addressing it doesn't need to get the RIP register.

The x86 payload is essentially the same thing as the x64 so this post only focuses on x64.

Since the NOP was a true NOP on x64, I overwrote the 40 90 with cc cc (int 3) using a hex editor. Interrupt 3 is how debuggers set software breakpoints.

Now when the system is exploited, our attached kernel debugger will automatically break when the shellcode starts executing.

Step 1: Find ntoskrnl.exe Base Address

Once the shellcode figures out it is x64 it begins to search for the base of ntoskrnl.exe. This is done with the following stub:

Fairly straightforward code. In user mode, the GS segment for x64 contains the Thread Information Block (TIB), which holds the Process Environment Block (PEB), a struct which contains all kinds of information about the current running process. In kernel mode, this segment instead contains the Kernel Process Control Region (KPCR), a struct which at offset zero actually contains the current process PEB.

This code grabs offset 0x38 of the KPCR, which is the "IdtBase" and contains a pointer struct of KIDTENTRY64. Those familiar with the x86 family will know this is the Interrupt Descriptor Table.

At offset 4 into the KIDENTRY64 struct you can get a function pointer to the interrupt handler, which is code defined inside of ntoskrnl.exe. From there it searches backwards in memory in 0x1000 increments (page size) for the .exe DOS MZ header (cmp bx, 0x5a4d).

Step 2: Locate Necessary Function Pointers

Once you know where the MZ header of a PE file is, you can peek into defined offsets for the export directory and get the relative virtual address (RVA) of any function you want. Userland shellcode does this all the time, usually to find necessary functions it needs out of ntdll.dll and kernel32.dll. Just like most userland shellcode, this ring 0 shellcode also uses a hashing algorithm instead of hard-coded strings in order to find the necessary functions.

The following functions are found:

ExAllocatePool can be used to create regions of executable memory, and ExFreePool can clean it up when done. These are important so the shellcode can allocate space for its hooks and other functions. ZwQuerySystemInformation is important in the next step.

Step 3: Locate Srv.sys SMB Driver

A feature of ZwQuerySystemInformation is a constant named SystemQueryModuleInformation, with the value 0xb. This gives a list of all loaded drivers in the system.

The shellcode then searched this list for two different hashes, and it landed on Srv.sys, which is one of the main drivers that SMB runs on.

The process here is basically equivalent to getting PEB->Ldr in userland, which lets you iterate loaded DLLs. Instead, it was looking for the SMB driver.

Step 4: Patch the SMB Trans2 Dispatch Table

Now that the DoublePulsar shellcode has the main SMB driver, it iterates over the .sys PE sections until it gets to the .data section.

Inside of the .data section is generally global read/write memory, and stored here is the SrvTransaction2DispatchTable, an array of function pointers that handle different SMB tasks.

The shellcode allocates some memory and copies over the code for its function hook.

Next the shellcode stores the function pointer for the dispatch named SrvTransactionNotImplemented() (so that it can call it from within the hook code). It then overwrites this member inside SrvTransaction2DispatchTable with the hook.

That's it. The backdoor is complete. Now it just returns up its own call stack and does some small cleanup chores.

Step 5: Send "Knock" and Raw Shellcode

Now when DoublePulsar sends its specific "knock" requests (which are seen as invalid SMB calls), the dispatch table calls the hooked fake SrvTransactionNotImplemented() function. Odd behavior is observed: normally the SMB response MultiplexID must match the SMB request MultiplexID, but instead it is incremented by a delta, which serves as a status code.

Operations are hidden in plain sight via steganography, which do not have proper dissectors in Wireshark.

The status codes (via MultiplexID delta) are:

  • 0x10 = success
  • 0x20 = invalid parameters
  • 0x30 = allocation failure

The opcode list is as follows:

  • 0x23 = ping
  • 0xc8 = exec
  • 0x77 = kill

You can tell which opcode was called by using the following algorithm:

t = SMB.Trans2.Timeout
op = (t) + (t >> 8) + (t >> 16) + (t >> 24);

Conversely, you can make the packet using this algorithm, where k is randomly generated:

op = 0x23
k = 0xdeadbeef
t = 0xff & (op - ((k & 0xffff00) >> 16) - (0xffff & (k & 0xff00) >> 8)) | k & 0xffff00

Sending a ping opcode in a Trans2 SESSION_SETUP request will yield a response that holds part of a XOR key that needs to be calculated for exec requests.

The "XOR key" algorithm is:

s = SMB.Signature1
x = 2 * s ^ (((s & 0xff00 | (s << 16)) << 8) | (((s >> 16) | s & 0xff0000) >> 8))

More shellcode can be sent with a Trans2 SESSION_SETUP request and exec opcode. The shellcode is sent in the "data payload" part of the packet 4096 bytes at a time, using the XOR key as a basic stream cipher. The backdoor will allocate an executable region of memory, decrypt and copy over the shellcode, and run it. The Inject DLL payload is simply some DLL loading shellcode prepended to the DLL you actually want to inject.

We can see the hook is installed at SrvTransaction2DispatchTable+0x70 (112/8 = index 14):

And of course the full disassembly listing.

Conclusion

There you have it, a highly sophisticated, multi-architecture SMB backdoor. The world probably did not need a remote Windows kernel payload this advanced being spammed across the Internet. It's an unique payload, because you can infect a system, lay low for a little bit, and come back later when you want to do something more intrusive. It also finds a nice place in the system to hide out and not alert built-in defenses like PatchGuard. It is unclear if newer versions of PatchGuard, such as those in Windows 10, already detect this hook. We can expect them to be added if not.

Usually we only get to see kernel shellcode in local exploits, as it swaps process tokens in order to privilege escalate. However, Microsoft does many networking things in the kernel, such as Srv.sys and HTTP.sys. The techniques demonstrated are in many ways completely analagous to how usermode shellcode operates during remote exploits.

If/when this gets ported over to Metasploit, I would probably not copy this verbatim, and rather skip the backdoor idea. It isn't the most secure thing to do, as it's not a big secret anymore and anyone else can come along and use your backdoor.

Here's what can be done instead:

  1. Obtain ntoskrnl.exe address in the same fashion as DoublePulsar, and read export directory for necessary functions to perform the next operations.
  2. Spawn a hidden process (such as notepad.exe).
  3. Queue an APC with Meterpreter payload.
  4. Resume process, and exit the kernel cleanly.

Every major malware family, from botnets to ransomware to banking spyware, will eventually add the exploits in the FuzzBunch toolkit to their arsenal. This payload is simply a mechanism to load more malware with full system privileges. It does not open new ports, or have any real encryption or other features to prevent others from taking advantage of the same hole, making the attribution game for digital forensic investigators even more difficult. This is a jewel compared to the scraps that were given to Stuxnet. It comes in a more dangerous era than the days of Conficker. Given the persistence of the missing MS08-067 patch, we could be in store for a decade of breaches emanating from MS17-010 exploits. It is the perfect storm for one of the most damaging malware infections in computing history.