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Tiny Deathstars of Foulness

Awhile back, I wrote a tool to rewrap ipa files that I called ipasign: https://github.com/krypted/ipasign/blob/master/ipasign.py. But I wanted to do something similar for the Mac, and specifically have it run in Linux. So looking at what you’d need to be able to do, let’s start with viewing the contents of a flattened Apple package.┬áThis command will show you the files installed as a part of the Node JS package. Why did I choose that package? It was sitting on my desktop…

pkgutil --files org.nodejs.node.pkg

Now, this logic is available because you’re running pkgutil on a Mac. But that can’t run in Linux. So what would you do if you wanted to complete that same operation? If the package hasn’t been flattened then you can simply traverse the files in the package. If it has been flattened (and it must be in order to properly be signed) then that can’t work. So to see the files installed from a Linux system will require a tad bit more work. First, we’ll create a directly to extract our package into:

mkdir node-v8.11.1.pkg

Then cd into that directory and use xar to extract the package:

xar -xf /Users/charles.edge/Downloads/node-v8.11.1.pkg

In there, you’ll see three files: Bom, PackageInfo, and Payload. The contents, which mimic the –files option to some extent are found by first changing the name of payload to Payload.gz:

mv ./node-v8.11.1.pkg/Payload ./node-v8.11.1.pkg/Payload.gz

Then unzipping it:

gunzip Payload

And viewing the contents:

cpio -iv < Payload

Or throw all that into a one-liner:

cpio -o | gzip -c > Payload

You can also use bomutils to traverse and make BOMs: http://bomutils.dyndns.org/tutorial.html

You can also see some metadata about how the package will lay down by catting the distribution file:

<?xml version=”1.0″ encoding=”utf-8″ standalone=”yes”?>
<installer-gui-script minSpecVersion=”1″>
<title>Node.js</title>
<welcome file=”welcome.html”/>
<conclusion file=”conclusion.html”/>
<background alignment=”topleft” file=”osx_installer_logo.png”/>
<pkg-ref id=”org.nodejs.node.pkg” auth=”root”>
<bundle-version/>
</pkg-ref>
<pkg-ref id=”org.nodejs.npm.pkg” auth=”root”>
<bundle-version/>
</pkg-ref>
<options customize=”allow” require-scripts=”false”/>
<license file=”license.rtf”/>
<choices-outline>
<line choice=”org.nodejs.node.pkg”/>
<line choice=”org.nodejs.npm.pkg”/>
</choices-outline>
<choice id=”org.nodejs.node.pkg” visible=”true” title=”Node.js v8.11.1″>
<pkg-ref id=”org.nodejs.node.pkg”/>
</choice>
<pkg-ref id=”org.nodejs.node.pkg” version=”v8.11.1″ onConclusion=”none” installKBytes=”37377″>#node-v8.11.1.pkg</pkg-ref>
<choice id=”org.nodejs.npm.pkg” visible=”true” title=”npm v5.6.0″>
<pkg-ref id=”org.nodejs.npm.pkg”/>
</choice>
<pkg-ref id=”org.nodejs.npm.pkg” version=”v5.6.0″ onConclusion=”none” installKBytes=”20113″>#npm-v5.6.0.pkg</pkg-ref>

If you want to make a package, check out this gist: https://gist.github.com/SchizoDuckie/2a1a1cc71284e6463b9a.

Next up, you frequently want to check the signature of a package. So to see the signature, I can simply use: pkgutil if on a Mac:

pkgutil --check-signature org.nodejs.node.pkg

Or I can use codesign:

codesign -v node-v8.11.1.pkg

The beauty of codesign is that it’s been open sourced by Apple. The bummer about codesign is that it uses multiple CoreFoundation frameworks:

otool -L /usr/bin/codesign

/usr/bin/codesign:

/System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1452.23.0)

/System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 58286.51.6)

/usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 400.9.0)

/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.50.4)

April 24th, 2018

Posted In: Mac OS X, Mac Security, Mass Deployment

Tags: , , , , , ,