An API is a contract between a caller and a callee. The most common forms of API abuse are caused by the caller failing to honor its end of this contract. For example, if a program fails to call chdir() after calling chroot(), it violates the contract that specifies how to change the active root directory in a secure fashion. Another good example of library abuse is expecting the callee to return trustworthy DNS information to the caller. In this case, the caller abuses the callee API by making certain assumptions about its behavior (that the return value can be used for authentication purposes). One can also violate the caller-callee contract from the other side. For example, if a coder subclasses SecureRandom and returns a non-random value, the contract is violated.
Example 2: The following code takes untrusted data and uses it to build a path which is used in a server side forward.
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String returnURL = request.getParameter("returnURL");
RequestDispatcher rd = request.getRequestDispatcher(returnURL);
rd.forward();
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<% String returnURL = request.getParameter("returnURL"); %>
<jsp:include page="<%=returnURL%>" />
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String returnURL = request.getParameter("returnURL");
return new ModelAndView(returnURL);
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<webflow:end-state id="finalStep" view="${requestParameters.url}"/>
<webflow:view-state id="showView" view="${requestParameters.test}">
<bean class="org.springframework.web.servlet.view.
InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
InternalResourceViewResolver will take the prefix it is configured with then concatenate the value passed in the view attribute and finally add the suffix.
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String returnURL = request.getParameter("returnURL");
return new ActionForward(returnURL);
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realloc() to resize buffers that store sensitive information. The function might leave a copy of the sensitive information stranded in memory where it cannot be overwritten.realloc() function is commonly used to increase the size of a block of allocated memory. This operation often requires copying the contents of the old memory block into a new and larger block. This operation leaves the contents of the original block intact but inaccessible to the program, preventing the program from being able to scrub sensitive data from memory. If an attacker can later examine the contents of a memory dump, the sensitive data could be exposed.realloc() on a buffer containing sensitive data:
plaintext_buffer = get_secret();
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plaintext_buffer = realloc(plaintext_buffer, 1024);
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scrub_memory(plaintext_buffer, 1024);
realloc() is used, so a copy of the data can still be exposed in the memory originally allocated for plaintext_buffer.VirtualLock to lock pages that contain sensitive data. The function is not always implemented.VirtualLock function is intended to lock pages in memory to prevent them from being paged to disk. However, on Windows 95/98/ME the function is implemented as stub only and has no effect.private and final, then mistakenly creates a method that mutates the Set.
@Immutable
public final class ThreeStooges {
private final Set stooges = new HashSet>();
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public void addStooge(String name) {
stooges.add(name);
}
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}