writes: David A. Wheeler, a computer scientist who is an acknowledged expert in developing secure open-source code, posted a message to the Open Source Software Security (oss-sec) list this evening urging more changes to the bash code. And other developers have found that the current patch still has vulnerabilities similar to the original one, where an attacker could store malicious data in a variable named the same thing as frequently run commands.
Norihiro Tanaka, a Japanese open-source developer, noted the problem in an e-mail to the bug-bash list today. By using an environmental variable called cat—the same name as a Unix utility that can concatenate files—he was able to bypass the fixes in the latest bash patch and pass through executable commands.
Wheeler noted this vulnerability as well, in an email to both oss-sec and the bug bash list:
I appreciate the effort made in patch bash43-026, but this patch doesn't even BEGIN to solve the underlying shellshock problem. This patch just continues the "whack-a-mole" job of fixing parsing errors that began with the first patch. Bash's parser is certain have many many many other vulnerabilities; it was never designed to be security-relevant. John Haxby recently posted that "A friend of mine said this could be a vulnerability gift that keeps on giving.” Bash will be a continuous rich source of system vulnerabilities until it STOPS automatically parsing normal environment variables; all other shells just pass them through! I've turned off several websites I control because I have *no* confidence that the current official bash patches actually stop anyone, and I am deliberately *not* buying products online today for the same reason. I suspect others have done the same. I think it's important that bash change its semantics so that it "obviously has absolutely no problems of this kind".
In other words, “Shellshock” may be partially patched, but it’s still highly dangerous on systems that might use bash to pass information to the operating system or to launch other software. And it may take a significant change to fix the code.