Turns out, the only way to trigger ‘RtlRunEncodeUnicodeString’ and ‘RtlRunDecodeUnicodeString’ on the master password entry dialog is by typing a character into it - which is fine, with one problem we locate the buffer after the character is inserted - which gives us an incomplete master password. Without this buffer, we would have to dive down the rabbit hole of the internals of Windows’ common controls and their associated memory management mechanisms to figure out where the memory buffer behind the master password edit control is (Which may be easy!, but we didn't take that route). We charted the output (Figure Below) by using details obtained from our tool. To craft a 1Password 4 version-agnostic exploit we needed to get a clearer picture of whats going on to identify how our master password was handled by 1Password 4’s workflows. So now we have a locked password vault, but with the encoded master password left residing in memory.Īnd to make matters worse, as we interact with the master password entry dialog, the same memory region is reused along with the same XOR byte value - giving us easy access to the encoded buffer to craft an exploit. However, upon unlocking 1Password 4 we notice that the encoded master password is not cleared from memory:Įven worse, it is still in memory after we lock 1Password 4. This isn't too bad, and apparently this is how all Windows’ native edit controls that are passed the ‘ES_PASSWORD’ flag to make it a masked password control, work.
‘RtlRunEncodeUnicodeString’ and ‘RtlRunDecodeUnicodeString’ are simple functions that mask a string using a single byte as the XOR value. Watching the buffer where the master password is stored.
#1password change master password code
The following image is of this tool ‘automagically’ identifying code areas in 1Password 4 that interact with the obfuscated password (In short, instructions that interact with data of interest, in this case, ‘Z3superpass#’, our master password, are flagged by this tool for further analysis). Instead, we’ll use an in-house tool (‘Thread Imager’) created for reverse engineering ‘weird’ proprietary protocols at the application layer to identify where 1Password 4 interacts with our master password.
This can get cumbersome and be an error prone process, especially with thick frameworks that have weird memory management that will require you to follow the buffer through numerous of copies and transformations. One could identify the message loop that captures keyboard and mouse activity by locating ‘GetMessage’, ‘PeekMessage’, ‘GetWindowText’ or other Window’s APIs that typically handle user input to locate the buffer our keystrokes are being captured into and following it until we reach an encryption/obfuscation routine. To find out why our master password is not in memory while it is clearly filled into the unlock dialog, we must locate the code that interacts with it. Is this good enough, should we leave it alone? Diving Deeper At most if my laptop were stolen or someone walked by to interact with my password manager they would be pitted against a locked vault.ġPassword must be encrypting or performing another form of obfuscation on the entry as we type it in. This is true for 1Password 4 (note, 1Password 7 is the latest version, however 1Password4 is the more ‘hardened’ version against these types of attacks, which is why its the focus of this blog), before I switched to it, years ago, I did a brief evaluation to confirm that my entries did not exist in memory once I placed it into a locked state, confirming they were carefully managed and removed from memory. I religiously kept my password manager locked, assuming a securely locked password manager would thwart any malicious activity and the most someone could steal is a bunch of random data since I trusted my password manager to scrub any sensitive entries from memory once I locked it. The Washington Post recently published an article based on our study of various password managers to spread awareness that not all password managers are created equal. With so much sensitive data entrusted into a single application, it’s important to understand what one’s exposure is in terms of credential loss on a compromised machine, be it malware, post exploitation scenarios (looking at you, Adobe Flash), or if you forget to lock your workstation when you walk away for a few minutes.
Myself, I have over 200 password entries. We love password managers they are great for many reasons. Down the RE’ing rabbit hole to exploit a fatal flaw in an otherwise great password manager (1Password 4).
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