Downloading old versions of Dropbox

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http://clientupdates.dropboxstatic.com/dbx-releng/client/dropbox-lnx.x86_64-23.4.19.tar.gz

https://dl.dropboxusercontent.com/u/17/Dropbox%2034.4.20.exe

Tweak the above URLs according to your needs.

Dropbox >= 34.4.20

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I have not analyzed Dropbox versions between 23.4.19 and 34.4.20.

The .dropbox-dist/dropbox-lnx.x86_64-34.4.20/dropbox file is no longer a ZIP file. This file seems to be a single-file combination of CPython + SQLite 3 + OpenSSL projects.

The obfuscated Python bytecode seems to be present in the python-packages.zip file.

The new versions of Dropbox can be decompiled by using the following steps,

$ export BLOB_PATH=.dropbox-dist/dropbox-lnx.x86_64-34.4.20/python-packages.zip

$ LD_PRELOAD=`pwd`/libdedrop.so .dropbox-dist/dropboxd

Decompile the decrypted .pyc files with uncompyle6.

It is also possible to decompile the python-packages.zip file from the Windows version of Dropbox under Linux by using this method.

Sniffing Dropbox traffic

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Build DynamoRIO and use the included "ssljack" plugin.

$ ~/dynamorio/build/bin64/drrun -c libssljack.so -- ~/.dropbox-dist/dropbox-lnx.x86_64-34.4.20/dropbox