[NEWS] JavaMail Information Disclosure (msgno)

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  JavaMail Information Disclosure (msgno)
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SUMMARY

"The  <http://java.sun.com/products/javamail/> JavaMail API provides a 
platform-independent and protocol-independent framework to build mail and 
messaging applications. The JavaMail API is implemented as a Java platform 
optional package and is also available as part of the Java 2 platform, 
Enterprise Edition. JavaMail provides a common, uniform API for managing 
electronic mail. It allows service-providers to provide a standard 
interface to their standards-based or proprietary messaging systems using 
the Java programming language. Using this API, applications access message 
stores, and compose and send messages. The JavaMail API is composed of a 
set of abstract classes that model the various pieces of a typical mail 
system."

The JavaMail API doesn't properly validate authenticated user message 
number attribute, allowing authenticated users to view other's messages.

DETAILS

Vulnerable Systems:
 * Solstice Internet Mail Server POP3 2.0
 * JavaMail API

The JavaMail API doesn't properly validate authenticated user message 
number attribute in MimeMessage constructor 
javax.mail.internet.InternetHeaders object, authenticated user is being 
able to access to others message requesting msgno. First attacker need to 
login to javamail from web with correct user name and password. Then the 
attacker will be able to request others message through msgno. Which means 
the attacker will be able to view all message from server.

The MimeMessage constructor holds its headers in 
javax.mail.internet.InternetHeaders object. This object, when constructed 
with an InputStream, reads lines from the stream until it reaches the 
blank line that indicates end of header. It stores the lines as RFC822 
header-fields. After the InternetHeaders object reads from the input 
stream, the stream is positioned at the start of the message body.

The POP3 implementation uses this constructor to load the message headers 
when one is requested:
public class POP3Message extends MimeMessage {
//Keep track of whether the Message data has been loaded
boolean loaded = false;
int hdrSize;
..
public String[] getHeader(String name) {
//Get the headers on demand from the message store
load();
// Don't need to reimplement getting the header object's contents
return super.getHeader(name);
}
/*** Reimplement all variants of getHeader() as above ***/
..
private synchronized void load() {
if (!loaded) {
// Get message data (headers and content) and cache it
content = POP3Command("RETR", msgno);
// Open a stream to the cache
InputStream is = new ByteArrayInputStream(content);
// Setup "headers" field by getting the header data
headers = new InternetHeaders(is);
// Save header size to easily access msg content from cache
hdrSize = content.length - is.available();
loaded = true;

This line make authenticated user to able to view others message through 
msgno :
content = POP3Command("RETR", msgno);

When user login and view his message and he may notice that
http://javamaildomain.com/ReadMessage.jsp?msgno=1000

User can do easily change msgno to whatever he want. If he entre valid 
message no, then he will be able to view others message.
http://javamaildomain.com/ReadMessage.jsp?msgno=10001
http://javamaildomain.com/ReadMessage.jsp?msgno=10002

Will not be his message number. And now user may know that he is accessing 
others message.


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> Thet Aung 
Min Latt.



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