Ken Thompson seems to hold the opinion, when it comes to trusting code, you have to trust the people writing the code that they won't include subtle backdoors and that it is impossible to review code to be non-malicious. So even when the code is Open Source, it doesn't mean others will spot subtle backdoors. (Not impossible, but too difficult and time consuming to work for any real life project.)
The moral is obvious. You can't trust code that you did not totally create yourself. (Especially code from companies that employ people like me.) No amount of source-level verification or scrutiny will protect you from using untrusted code. In demonstrating the possibility of this kind of attack, I picked on the C compiler. I could have picked on any program-handling program such as an assembler, a loader, or even hardware microcode. As the level of program gets lower, these bugs will be harder and harder to detect. A well installed microcode bug will be almost impossible to detect.
His examples demonstrates that with C code.
I am also referring to The Underhanded C Contest / [Hiding Backdoors in plain sight] (backdoorhiding.appspot.com).
Is this an exclusive issue with C and by extension with C++ as well?
Is this an issue for lower level languages, let's say assembler code?
Is this an issue, with higher level languages, let's say python code?