Exploiting MMS Vulnerabilities to Stealthily Exhaust Mobile Phone’s Battery Radmilo Racic Denys Ma Hao Chen University of California, Davis
Jan 19, 2016
Exploiting MMS Vulnerabilities to Stealthily Exhaust Mobile
Phone’s Battery
Radmilo Racic
Denys Ma
Hao Chen
University of California, Davis
Is it only the network?
Assume the network is perfect…
Why target the cell phone?
• Batteries are bottlenecks
• Cellular phones are poorly protected
• Cell phones attackable from the Internet
Why exploit a cellular network?
• Part of our critical infrastructure
• Eggshell security
• Connected to the Internet
Goals
1. Exhaust a cell phone’s battery
2. Attack cell phones stealthily
“Sleep deprivation” attack
Approach:Prevent a cell phone from sleeping
Procedure:• Identify victims (utilizing MMS)• Deliver attack (utilizing GPRS)
MMS architecture
Wireless Net
Wireless Net
Internet
Bill
George Sr.
George Jr.
MMS R/S
MMS R/S
SMTP
SMTP
SMTP
MMS vulnerabilities
• Messages unencrypted
• Notifications unauthenticated
• Relay server unauthenticated
• Cell phone information disclosure– IP address, platform, OS, etc.– Exploited to build a hit list
GPRS Overview• Overlay over GSM• Connected to the Internet through a gateway
(GGSN)• Each phone establishes a packet data protocol
(PDP) context before each Internet connection.• PDP context is a mapping between GPRS and
IP addresses.
GPRS cell phone state machine
Prevent a cell phone from sleeping
1. Activate a PDP context• By utilizing MMS notifications
2. Send UDP packets to cell phone• Just after the READY timer expires• To tax its transceiver
Attack
Attacker
Attack Server
MMS Notification
HTTP Request
UDP Packets
Victim(410) 555-1980
Attack details
• Surreptitious to both the user and network
• Works on various phones
• Works on multiple providers
• Requires few resources– Internet connection– Less than a 100 lines of python attack code
Battery life under attack
0
20
40
60
80
100
120
140
160
180
Nokia 6620 Sony T610 Motorola v710
Min
ute
sNormal Use Time
Under Attack Time
Reduction: 22.3:1 8.5:1 18:1
156
6036
7 7 2
Attack scale
• Send a UDP packet to– a GSM phone every 3.75s, or– a CDMA phone every 5s
• Using a home DSL line (384 kbps upload) can attack simultaneously– 5625 GSM phones, or– 7000 CDMA phones
Attack improvements
• TCP ACK attack: force the phone to send as well as receive data– Receiver will reply with RST or empty packet
• Packets with maximum sized payload
• Attack effective through NATs and Firewalls– Because the victim’s cell phone initiates the
connection to the attack server
Sources of vulnerabilities
• MMS allows hit list creation
• MMS allows initiation of a PDP context
• GPRS retains the PDP context
MMS hardening
• Authenticate messages and servers
• Hide information at WAP gateway
• Filter MMS messages
PDP Context Management
• Implement a defense strategy at GGSN– GGSN stateful
• PDP context modification message is already present– Transparent to the end user– NAT-like behavior
Related works
• SMS analysis [Enck et al, CCS05]– Focuses on SMS– Attacks the network
• Mobile viruses [Bose et al, yesterday]– Propagation of worms on cellular networks
• Control channels [Agarwal, NCC04]– Capacity analysis of shared control channels
Conclusion
• Demonstrated an attack that drains a phone’s battery up to 22 times faster
• Can attack 5625-7000 phones using a home DSL line
• Attack is surreptitious• Attack effective on multiple phones and
networks• Suggested mitigation strategies
Future work
• Worm deployment strategies targeting MMS vulnerabilities
• Battery attacks initiated from cell phones
Thank you
http://zeus.cs.ucdavis.edu/cellSecurity
Results
18:1236Motorola V710
8.5:1760Sony-E T610
22.3:17156Nokia 6620
Reduction Rate Under Attack (Hr)Normal (Hr)Phone
Battery Life