Page 10 - Technical report on SS7 vulnerabilities and mitigation measures for digital financial services transactions

Abbreviations and acronyms

BTS Base Transceiver Station for 2G/3G also know as cell tower
CISO Chief Information Security Officer
DFS Digital Financial Service
eNodeB Base station for LTE a.k.a cell tower (LTE radio access element)
ENISA European Union Agency for Network and Information Security
GTP GPRS Tunnelling Protocol
GSMA GSM Association
HLR & VLR Home / Visitor Location Register, the central database that holds the telco’s
subscriber’s information, both native and roaming subscribers.
IMEI International Mobile Equipment Identity; An identifier used by the telecom
network to uniquely identify a UE.
IMSI & TMSI International Mobile Subscriber Identity; The mobile subscriber unique identifier,
used internally in the telecom network.
LTE Long Term Evolution, the fourth generation of cellular networks more commonly
known as 4G
MAP Mobile Application Part, an SS7 protocol that defines the signalling required
for mobile, e.g. roaming, calling, SMS etc.
MO-SMS Mobile Originated SMS, an SMS sent from the UE to the network.
MO-USSD Mobile Originated USSD transaction, a USSD transaction initiated by the UE.
MSISDN Mobile Station International Subscriber Directory Number
MT-SMS Mobile Terminated SMS, an SMS sent from the network to the UE.
MT-USSD Mobile Terminated USSD transaction, a USSD transaction initiated by the mobile
network to a specific UE
MOU Memorandum of Understanding
OTP One Time Password.
POP Post Office protocol
PIN Personal Identification Number
SMS Short Messaging Service
SS7 Signalling System No. 7—The signalling protocol used for interconnection between
telecom networks and between internal sub components of each telecom network
(land and mobile networks alike)
STK Sim Tool Kit
Telco Telecom Operator
UE User Equipment, the user’s end device, in our case the mobile phone (feature
or smart)
USSD Unstructured Supplementary Service Data

8 • Technical report on SS7 vulnerabilities and mitigation measures for digital financial services transactions