[ISN] Hackers hijack county phones

InfoSec News isn at c4i.org
Wed Nov 24 08:59:29 EST 2004


By Les Gehrett
For the Gazette-Times
November 24, 2004

ALBANY - Hackers broke into the Linn County government's phone system
earlier this month and billed the county for many hours worth of
expensive international calls.

The county has fixed the problem and is working with phone company
fraud investigators to sort out the charges.

Linda Penick, an administrative assistant in the county's general
services division in charge of telecommunications, said the problem
seems to have begun over the weekend of Nov. 13-14.

She said hackers began by calling the main dial-in number for various
county departments. Using the voicemail system, they reached
individual employee voicemail boxes.

The hackers then tried to figure out each employee's password, so that
they could change the greeting on the employee's voicemail. This
turned out to be pretty easy to do in some cases, because a few
employees were using their extension number as their voicemail

Once the hackers figured out the password, they recorded a new
greeting. This new greeting was basically, "Hello. Yes, I'll accept
the charges."

This was done to between 10 and 20 county phone lines. These phone
lines were then used to authorize third-party collect calls overseas.  
Callers would simply make collect phone calls, say that they wanted to
bill the call to a home phone, and give a county employee's phone
number as the home number.

When the operator dialed the county number, the altered voicemail
system kicked in, answered the phone and authorized the billing.

Penick said county departments were contacted by fraud investigators
from MCI on Monday, Nov. 15. The departments referred the problems to
her, since she handles the county's phone system.

"I spent all week fighting through this and trying to figure out what
they had done," Penick said.

She thinks that once the phone system was broken into, the hackers
publicized and sold the access numbers. Throughout the week, employees
continued to receive a barrage of phone calls from operators asking
them to authorize the collect phone calls. The employees, of course,

Penick said county employees have been told to change their voicemail
passwords and to not use their extension number as their password. She
has also changed their system so that third-party collect calls cannot
by billed to the county.

County departments will continue to accept legitimate collect calls
from residents of the county.

Debbie Lewis, a spokeswoman for MCI, said this is a common scheme.

"This is one way that intruders try to damage the integrity of a phone
system for their own illegal activities," Lewis said.

To guard against such an attack, Lewis said companies and government
agencies should work closely with their internal phone system vendors
to follow proper security measures. Passwords should be long enough
that they are difficult to hack, and they should never be based on
birthdays or social security numbers.

Passwords should also be varied, not using either a single number,
such as "9999" or a sequential number, such as "1234."

Penick said the total amount of fraudulent charges has not been
determined, but she doesn't think the county will be stuck with the

"It's my understanding that we'll be able to contact them and get the
charges dropped," Penick said.

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