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7-Zip: From Uninitialized Memory to Remote Code Execution

landave.io

1–10 of 121 posts

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#2
7-Zip needs to start a Go Fund Me or similar for a Code Signing certificate. They're like $69-89/year, which is expensive, but for such a popular piece of software it would be a nice safety net in case of site compromise.

Too bad none of the big CAs have an Open Source/Charity program that would provide a Authenticode Certificate for use with that software.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#3

7-Zip needs to start a Go Fund Me or similar for a Code Signing certificate. They're like $69-89/year, which is expensive, but for such a popular piece of software it would be a nice safety net in case of site compromise. Too bad none of the big CAs have an Open Source/Charity program that would provide a Authenticode Certificate for use with that software.

That's surprising. I'd expect they receive more than $70 a year in donation already, so it should not be such a big issue.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#4

7-Zip needs to start a Go Fund Me or similar for a Code Signing certificate. They're like $69-89/year, which is expensive, but for such a popular piece of software it would be a nice safety net in case of site compromise. Too bad none of the big CAs have an Open Source/Charity program that would provide a Authenticode Certificate for use with that software.

That's surprising. I'd expect they receive more than $70 a year in donation already, so it should not be such a big issue.

I've never found (recently) how to donate to 7-zip, it seems the author removed the option to do so on the website. Maybe I'm too stupid, so please correct me if I'm wrong and you find a link.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#5

7-Zip needs to start a Go Fund Me or similar for a Code Signing certificate. They're like $69-89/year, which is expensive, but for such a popular piece of software it would be a nice safety net in case of site compromise. Too bad none of the big CAs have an Open Source/Charity program that would provide a Authenticode Certificate for use with that software.

> Go Fund Me

I second it. The thing with donations is many people assume that someone is gonna donate (including me) and click "not now or later", where as in gofundme we would see how much they raised out of total goal and many people will then put the money.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#6

7-Zip needs to start a Go Fund Me or similar for a Code Signing certificate. They're like $69-89/year, which is expensive, but for such a popular piece of software it would be a nice safety net in case of site compromise. Too bad none of the big CAs have an Open Source/Charity program that would provide a Authenticode Certificate for use with that software.

That could be a nice use case for a blockchain.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#7
There were some misunderstandings that I want to clear up (maybe I will add them in an update to the blog post):

1. Some people mentioned that this would "only affect RAR files" and it would be safe to extract 7z files with 7-Zip prior to version 18.05. This is wrong, because 7-Zip detects the file type from the magic numbers at the beginning of the file. So the exploit can be renamed to 'exploit.7z' and it works just as well.

On /r/sysadmin, someone even mentioned that a temporary solution might be to block RAR files. By the same argument, this is unlikely to be effective.

2. Almost all versions prior to 18.05 are affected. I manually checked version 15.05 and 17.01, and they are definitely affected.

3. Not only 7-Zip itself is affected, but essentially all software that uses 7z.dll as library to extract files. This includes various anti-virus software. However, exploitation may be more difficult (though not impossible) if ASLR&DEP is properly enabled (on all modules).

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#8
post #7

There were some misunderstandings that I want to clear up (maybe I will add them in an update to the blog post): 1. Some people mentioned that this would "only affect RAR files" and it would be safe to extract 7z files with 7-Zip prior to version 18.05. This is wrong, because 7-Zip detects the file type from the magic numbers at the beginning of the file. So the exploit can be renamed to 'exploit.7z' and it works jus…

This includes various anti-virus software.

It's fascinating that this category of equipment, which searches for viruses by running untrusted code, is still regularly installed in all corners of valuable networks.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#9

7-Zip needs to start a Go Fund Me or similar for a Code Signing certificate. They're like $69-89/year, which is expensive, but for such a popular piece of software it would be a nice safety net in case of site compromise. Too bad none of the big CAs have an Open Source/Charity program that would provide a Authenticode Certificate for use with that software.

IIRC 7-Zip has explicitly decided not go get signed. It doesn’t help all that much anyway, SmartScreen still catches your application and nags the user.

Unfortunately, I cannot seem to find any reference, so I might remember it wrong or it wasn’t about 7-Zip or whatever. The thing with SmartScreen is (unfortunately) still true.

Re: 7-Zip: From Uninitialized Memory to Remote Code Execution

#10
post #7

There were some misunderstandings that I want to clear up (maybe I will add them in an update to the blog post): 1. Some people mentioned that this would "only affect RAR files" and it would be safe to extract 7z files with 7-Zip prior to version 18.05. This is wrong, because 7-Zip detects the file type from the magic numbers at the beginning of the file. So the exploit can be renamed to 'exploit.7z' and it works jus…

I have previously read that for some reason the author disables most of the compiler options for things like ASLR and DEP

I never managed to find out why

edit: just found this: https://sourceforge.net/p/sevenzip/feature-requests/1270/ -- seems rather questionable considering MS give away the latest compilers for free

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