TL;DR: if you use redis-namespace and you use
Kernel#exec may get called. Please upgrade to 1.0.4, 1.1.1, 1.2.2, or 1.3.1 immediately.
Redis has an EXEC command. We handle commands through
method_missing. This works great, normally:
r = Redis::Namespace.new("foo") r.exec # => error, not in a transaction, whatever
Here’s the problem:
Kernel#exec. Since this is on every object, when you use
#send, it skips the normal visibility, and calls the private but defined
Kernel#exec rather than the
r = Redis::Namespace.new("foo") r.send(:exec, "ls") # => prints out your current directory
We fix this by not proxying
You are only vulnerable if you do the always-dangerous ‘send random input to an object through
send.’ And you probably don’t. A cursory search through GitHub didn’t find anything that looked vulnerable.
However, if you write code that wraps or proxies Redis in some way, you may do something like this.
The official Redis gem does not use
method_missing, so it should not have any issues: https://github.com/redis/redis-rb/blob/master/lib/redis.rb#L2133-L2147
I plan on removing the
method_missing implementation in a further patch, but since this is an immediate issue, I wanted to make minimal changes.
Testing this is hard,
#exec replaces the current running process. I have verified this fix by hand, but writing an automated test seems difficult.