| /wiki/EvalArbitraryCodeExecution.wiki r0 | /wiki/EvalArbitraryCodeExecution.wiki r15 | ||
| 1 | =Eval and Function Constructor allow Execution of Unrewritten Javascript= | ||
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| 2 | |||
| 3 | ==Effect== | ||
| 4 | Execute arbitrary code with access to the global environment, and the local members of the stack frame in which it is called. | ||
| 5 | |||
| 6 | |||
| 7 | ==Background== | ||
| 8 | eval is described at 15.1.2.1, and parses its argument as a Program, and executes it in it's caller's environment. | ||
| 9 | |||
| 10 | The Function constructor allows creation of a function given a string body. It will execute in the global scope as described at EcmaScript 262 section 15.3.2.1 | ||
| 11 | |||
| 12 | EcmaScript 262 specifically requires that the global eval method be assignable, so it can be replaced. The Function constructor is available via the 'constructor' property of any function object. | ||
| 13 | |||
| 14 | |||
| 15 | ==Assumptions== | ||
| 16 | window.eval and/or the Function constructor are accessible. The function constructor is available if any function is available and a function's constructor property is readable. | ||
| 17 | |||
| 18 | |||
| 19 | ==Versions== | ||
| 20 | All interpreters that obey the referenced sections of EcmaScript. | ||
| 21 | |||
| 22 | |||
| 23 | ==Example== | ||
| 24 | {{{ | ||
| 25 | eval('alert("your cookie is " + document.cookie)'); | ||
| 26 | |||
| 27 | (new Function('alert("your cookie is " + document.cookie)'))(); | ||
| 28 | }}} | ||