SHA3 Hashes (on Windows) - Where Art Thou?
No sooner had posted on doing file and string hashes in PowerShell, when I (again) got asked by Jim - "What about SHA3? Shouldn't we be using Quantum Safe algorithms if we have them?"
Looking around, support for SHA3 is pretty sparse no matter what the OS. For Windows there's a decent solution in bouncycastle (https://www.bouncycastle.org/), but the install is likely more than folks want to tackle, especially if it gets rolled into PowerShell at some future date. Similarly, the SCCM ConfigurationManager module does implement them in some fashion, but that's kind of a dead-end for most of us too.
In a pinch, hashify.net has a public API that supports just about any hashing algorithm you'd care to mention:
curl --location --request GET "api.hashify.net/hash/sha3-512/hex?value=CQCQCQ"
{"Digest":"bcc7a070db5dd926bfbef21c6c5e8081402a79e45f96c4cd7fedc405e1a7fcb6b047cff266235f19f0d1219d2f0fd9299b93cd28d69517d7aefec8cf0c9ffdcc","DigestEnc":"hex","Type":"SHA3-512","Key":""}
The problem with that is - if the information you are hashing (presumably to verify against either now or later) is important or sensitive enough to warrant using one of the fancy SHA3 algorithms, it's likely not data that you want sent to a public website in the clear.
I eventually decided to use the functionality in OpenSSL, with the rationale that anyone who needs this function will likely have OpenSSL already installed locally, at most we'd be asking them to upgrade - you'll need OpenSSL 1.1.1 or better for SHA3-xxx hash support. The syntax is:
echo "some string" | openssl dgst -hashalgorithm
or
type "somefilespec" | openssl dgst -hashalgorithm
where "hashalgorithm" is any of:
blake2b512 blake2s256 md4
md5 md5-sha1 mdc2
ripemd ripemd160 rmd160
sha1 sha224 sha256
sha3-224 sha3-256 sha3-384
sha3-512 sha384 sha512
sha512-224 sha512-256 shake128
shake256 sm3 ssl3-md5
ssl3-sha1 whirlpool
So for implementing this in PowerShell, it's as easy as creating the command in a string, then calling it with "Invoke-Expression" (shortened to "iex" in the examples below).
So for now, until Microsoft rolls better support for SHA3 family of hashing algorithms, my quick-and-dirty implementation for the newer, shinier hash algorithms is below. Note that if OpenSSL isn't in the path, I've got a variable pointed to the path to the binary (update this variable to match your install). In any "real" code you would put this in a config file of course (because we all need more config files in our life right?)
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$OpenSSLPath = "C:\openssl-1.1.1h\bin\" function Get-StringHash-OpenSSL ( [String] $InputString, $HashAlgo ) { $QT = "`"" $cmd = "echo " + $QT + $InputString + $QT + " | " + $OpenSSLPath + "openssl.exe dgst -" + $HashAlgo $callcmd = iex $cmd $callcmd.split(" ")[1] } $hash = get-stringhash-openssl "CQ CQ CQ" "SHA3-256" $hash 5b960a5284843bb23af5e249c8692bd6d831645cc5070d501b4cef3e94d6983e |
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$OpenSSLPath = "C:\openssl-1.1.1h\bin\" function Get-FileHash-OpenSSL ( [String] $InputFileSpec, $HashAlgo ) { $QT = "`"" $cmd = "type " + $QT + $InputFileSpec + $QT + " | " + $OpenSSLPath + "openssl.exe dgst -" + $HashAlgo $callcmd = iex $cmd $callcmd.split(" ")[1] } $hash = get-FileHash-OpenSSL "c:\windows\system32\cmd.exe" "Sha3-512" $hash 0cacd8c85b44eed57101fee1431434278319dc441aee26354f811b483a30ff7861ecc88f4c90791e941e49dcb124a975d9eb301 |
If you've worked out a way to get these algorithms into PowerShell without IEX or any 3rd party installs, please share using our comment form.
(And yes, I did riff on the title of Mark Baggett's presentation next week - Tech Tuesday Workshop - O Hacker, Where Art Thou?: A Hands-On Python Workshop for Geolocating Attackers https://www.sans.org/webcasts/hacker-art-thou-hands-on-python-workshop-geolocating-attackers-115340 )
===============
Rob VandenBrink
www.coherentsecurity.com
Hashes in PowerShell
As a follow up to yesterday's how-to, I thought hashing might a thing to cover. We use hashes all the time, but it's annoying that md5sum, sha1sum and sha256sum aren't part of the windows command set - or are they? Yup, it turns out that they most definitely are part of PowerShell:
Get-FileHash -path $filename -Algorithm $algo
Where the Algorithm is a string, any one of:
"SHA1","SHA256","SHA384","SHA512","MACTripleDES","MD5","RIPEMD160"
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$a = get-filehash -Path .\somefile.txt -Algorithm SHA256 $a Algorithm Hash Path $a.Hash |
But what about string values? If you want to hash a string, there doesn't seem to be a function for that. It turns out that while it's not part of PowerShell as a separate thing, it's pretty easy to access it using the string as an "inputstring" variable:
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$stringAsStream = [System.IO.MemoryStream]::new() $writer = [System.IO.StreamWriter]::new($stringAsStream) $writer.write("RADIO CHECK") $writer.Flush() $stringAsStream.Position = 0 Get-FileHash -Algorithm "SHA256" -InputStream $stringAsStream | Select-Object Hash Hash ---- A450215BE7B1BC6006D41FF62A9324FEB4CD6D194462CB119391CE21555658BB |
So, this gets the job done but it's a bit cludgy, let's drop it into a function, then call the function:
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function Get-StringHash ( [String] $InputString, $HashAlgo) { $stringAsStream = [System.IO.MemoryStream]::new() $writer = [System.IO.StreamWriter]::new($stringAsStream) $writer.write($InputString) $writer.Flush() $stringAsStream.Position = 0 Get-FileHash -Algorithm $HashAlgo -InputStream $stringAsStream | Select-Object Hash } $a = get-stringhash "LOUD AND CLEAR" "SHA256" $a Hash ---- 7FE22308D7B971EDCADB8963188E46220E9D5778671C256216AEA712A33D4A3E $a.Hash 7FE22308D7B971EDCADB8963188E46220E9D5778671C256216AEA712A33D4A3E |
This "common infosec functions in PowerShell" thing kinda got started by accident, and got extended when Jim Clausing asked me if I was going to re-write CyberChef in PowerShell?. Of course my answer was "If you're going to put down a dare like that, challenge accepted" - so look for more stories of this type in future. As I introduce more functions, I'll roll them into the same GUI as I presented yesterday, code will get updated in my github ( https://github.com/robvandenbrink ).
===============
Rob VandenBrink
www.coherentsecurity.com
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