There is a vulnerability in uml_net. The latest version is vulnerable too.

The problem is the lack of bounds checking in uml_net.c from uml_utilities,

A possible attack could lead to root compromise on some systems since for

example uml_net comes suided root in RH 8.0 by default.

Let's look over the code:

* int n = 3, v;

we observe how "v" is declared, as a signed integer.

with a little bit of "luck" will end up here, knowing that "v" will get

the value of the first parameter (an integer) given to the program:

* if(v > CURRENT_VERSION)

so... if "v" is smaller than 0, the test will be passed but "v" will not

be between 0 and CURRENT_VERSION as the author would expected to.

after some tests on the second parameter of the program... we should

arrive to this code:

* if(handlers[v] != NULL) (*handlers[v])(argc - n, &argv[n]);

here it is called the function located at handlers[v]. by suplying a large

negative integer for "v", handlers[v] can point to the stack which can be

controlled by the user. so, the program can be fooled to call a user

controlled "function".

since the root privileges are not dropped till this point... the user code

will be executed with super-user privileges.

Suggested patch: uml_net.c

- if(v > CURRENT_VERSION){

+ if ((v > CURRENT_VERSION) || (v < 0)) {

Contact: ktha (at) hushmail (dot) com [email concealed]

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