GSM Pentesting - Revision history

Ikramer at 18:24, 12 March 2024

2024-03-12T18:24:56Z

← Older revision		Revision as of 18:24, 12 March 2024
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	[[Category:Documentation]]		[[Category:Documentation]]
			[[Category:Pentesting]]

FVarli at 16:45, 8 July 2021

2021-07-08T16:45:09Z

← Older revision		Revision as of 16:45, 8 July 2021
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	IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.		IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.


	=== Encryption ===		=== Encryption ===
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	The website shows Osmocom-compatible mobile phones and laptops, which are visualized on a map.		The website shows Osmocom-compatible mobile phones and laptops, which are visualized on a map.



	== References ==		== References ==

FVarli at 16:44, 8 July 2021

2021-07-08T16:44:58Z

← Older revision		Revision as of 16:44, 8 July 2021
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	=== Fake Basesstation & IMSI-Catcher ===		=== Fake Basesstation & IMSI-Catcher ===

	The problem with GSM is the lack of authentication between the base station (BTS) and the end device. This enables a “man in the middle” attack to be carried out with a “rogue base station”/IMSI catcher. To do this, the system must be placed near the person to be spied on. By increasing the transmission power, the ME located in the vicinity are made to connect to this station of the attacker If the IMSI number of the person to be intercepted is not yet known, it must first be identified from the multitude of telephone calls made in the area. Professional devices such as the GA-901 from “Rohde & Schwarz” can therefore record several channels at the same time. This means that uninvolved people can also be eavesdropped. With this method, only outgoing phone calls can be eavesdropped. The outgoing call is forwarded to a "real" BTS. The so-called "MITM impersonation" uses the "Dynamic SIM cloning" method to position oneself in the uplink and also in the downlink channel between the communication partners. An "IMSI request" prompts the ~~handset~~ to disclose this unique number, which rarely occurs in normal operation. This allows movement profiles to be created, although this is to be prevented by the TMSI.		The problem with GSM is the lack of authentication between the base station (BTS) and the end device. This enables a “man in the middle” attack to be carried out with a “rogue base station”/IMSI catcher. To do this, the system must be placed near the person to be spied on. By increasing the transmission power, the ME located in the vicinity are made to connect to this station of the attacker If the IMSI number of the person to be intercepted is not yet known, it must first be identified from the multitude of telephone calls made in the area. Professional devices such as the GA-901 from “Rohde & Schwarz” can therefore record several channels at the same time. This means that uninvolved people can also be eavesdropped. With this method, only outgoing phone calls can be eavesdropped. The outgoing call is forwarded to a "real" BTS. The so-called "MITM impersonation" uses the "Dynamic SIM cloning" method to position oneself in the uplink and also in the downlink channel between the communication partners. An "IMSI request" prompts the Mobile Equipment to disclose this unique number, which rarely occurs in normal operation. This allows movement profiles to be created, although this is to be prevented by the TMSI.

	IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.		IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.

FVarli at 16:43, 8 July 2021

2021-07-08T16:43:05Z

← Older revision		Revision as of 16:43, 8 July 2021
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	== Summary ==		== Summary ==

	This article describes two possible attack vectors in the GSM protocol. It is actually possible to do ~~this~~ with open-source solutions. The only problem is the legal and technical situation, whether there is a way to keep the output power so low that only our devices connect to the base station, otherwise legal consequences follow if other devices and Signals are involved.		This article describes two possible attack vectors in the GSM protocol. It is actually possible to do these attacks with open-source solutions. The only problem is the legal and technical situation, whether there is a way to keep the output power so low that only our devices connect to the base station, otherwise legal consequences follow if other devices and Signals are involved.

	== Description ==		== Description ==
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	=== Fake Basesstation & IMSI-Catcher ===		=== Fake Basesstation & IMSI-Catcher ===

	The problem with GSM is the lack of authentication between the base station (BTS) and the end device. This enables a “man in the middle” attack to be carried out with a ~~“bogus~~ base station” ~~or an~~ IMSI catcher. To do this, the system must be placed near the person to be spied on. By increasing the transmission power, ~~those~~ in the vicinity are		The problem with GSM is the lack of authentication between the base station (BTS) and the end device. This enables a “man in the middle” attack to be carried out with a “rogue base station”/IMSI catcher. To do this, the system must be placed near the person to be spied on. By increasing the transmission power, the ME located in the vicinity are made to connect to this station of the attacker If the IMSI number of the person to be intercepted is not yet known, it must first be identified from the multitude of telephone calls made in the area. Professional devices such as the GA-901 from “Rohde & Schwarz” can therefore record several channels at the same time. This means that uninvolved people can also be eavesdropped. With this method, only outgoing phone calls can be eavesdropped. The outgoing call is forwarded to a "real" BTS. The so-called "MITM impersonation" uses the "Dynamic SIM cloning" method to position oneself in the uplink and also in the downlink channel between the communication partners. An "IMSI request" prompts the handset to disclose this unique number, which rarely occurs in normal operation. This allows movement profiles to be created, although this is to be prevented by the TMSI.
	~~Brought ME~~ to connect to this attacker~~'s station.~~ If the IMSI number of the person to be intercepted is not yet known, it must first be identified from the multitude of telephone calls made in the area. Professional devices such as the GA-901 from “Rohde & Schwarz” can therefore record several channels at the same time. This means that uninvolved people can also be eavesdropped. With this method, only outgoing phone calls can be eavesdropped. The outgoing call is forwarded to a "real" BTS. The so-called "MITM impersonation" uses the "Dynamic SIM cloning" method to position oneself in the uplink and also in the downlink channel between the communication partners. An "IMSI request" prompts the handset to disclose this unique number, which rarely occurs in normal operation. This allows movement profiles to be created, although this is to be prevented by the TMSI.

	IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.		IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.
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	=== Encryption ===		=== Encryption ===

	The encryption algorithm A5 is used on the air interface between the ME and the BTS. When A5 / 1 and A5 / 2 were developed in the late 1980s, the decision was made to use "Security By Obscurity", which ~~is to say~~ that the security of the process depends on the algorithm being kept secret. By 1999, both stream cipher methods were investigated by Marc Briceno and other scientists using reverse engineering and finally published.		The encryption algorithm A5 is used on the air interface between the ME and the BTS. When A5 / 1 and A5 / 2 were developed in the late 1980s, the decision was made to use "Security By Obscurity", which means that the security of the process depends on the algorithm being kept secret. By 1999, both stream cipher methods were investigated by Marc Briceno and other scientists using reverse engineering and finally published.
	An attack on A5 / 1 was carried out by A. Biryukov, A. Shamir, and D. Wagner in 2000. The complexity of the original ~~264~~ has been reduced to ~~238~~ and ~~248~~ respectively. In the meantime, “Rainbow Tables” ~~15, 16~~ are used to decrypt the A5 / 1. This technology shortens the computational effort in order to calculate back the correct session key, with which it is then possible to passively listen in on phone calls in real time. A modified cell phone of an older design is completely sufficient for this. A5 / 1 is used in Europe and the USA. The much weaker A5 / 2 was developed for countries where strong encryption is prohibited. According to the standardization committee, this algorithm has not been allowed to be used since 2007.
			An attack on A5 / 1 was carried out by A. Biryukov, A. Shamir, and D. Wagner in 2000. The complexity of the original 2^64 has been reduced to 2^38 and 2^48 respectively. In the meantime, “Rainbow Tables” are used to decrypt the A5 / 1. This technology shortens the computational effort in order to calculate back the correct session key, with which it is then possible to passively listen in on phone calls in real time. A modified cell phone of an older design is completely sufficient for this. A5 / 1 is used in Europe and the USA. The much weaker A5 / 2 was developed for countries where strong encryption is prohibited. According to the standardization committee, this algorithm has not been allowed to be used since 2007.

	With UMTS, only A5 / 3 is used to encrypt the radio connection. Also known as KASUMI, the procedure was published in 2002. However, more security is only created by the increased complexity of the block cipher procedure. In the GSM network sections between BTS, BSC and MSC, the data is not encrypted and is transmitted via radio link if required, which means that passive eavesdropping or the interception of the session key is possible at these points.		With UMTS, only A5 / 3 is used to encrypt the radio connection. Also known as KASUMI, the procedure was published in 2002. However, more security is only created by the increased complexity of the block cipher procedure. In the GSM network sections between BTS, BSC and MSC, the data is not encrypted and is transmitted via radio link if required, which means that passive eavesdropping or the interception of the session key is possible at these points.
	An up-to-date overview of the security level of those in use: ~~The GSM-MAP project is intended to enable cellular networks~~. The website shows Osmocom-compatible mobile phones and laptops, which are visualized on a map.		An up-to-date overview of the security level of those cellular networks in use:
	~~Link: https://gsmmap.org~~
			''Link: https://gsmmap.org''

			The website shows Osmocom-compatible mobile phones and laptops, which are visualized on a map.



	== References ==		== References ==

FVarli: Created page with "== Summary == This article describes two possible attack vectors in the GSM protocol. It is actually possible to do this with open-source solutions. The only problem is the..."

2021-07-08T16:35:16Z

Created page with "== Summary == This article describes two possible attack vectors in the GSM protocol. It is actually possible to do this with open-source solutions. The only problem is the..."

New page

== Summary ==

This article describes two possible attack vectors in the GSM protocol. It is actually possible to do this with open-source solutions. The only problem is the legal and technical situation, whether there is a way to keep the output power so low that only our devices connect to the base station, otherwise legal consequences follow if other devices and Signals are involved.

== Description ==

=== Fake Basesstation & IMSI-Catcher ===

The problem with GSM is the lack of authentication between the base station (BTS) and the end device. This enables a “man in the middle” attack to be carried out with a “bogus base station” or an IMSI catcher. To do this, the system must be placed near the person to be spied on. By increasing the transmission power, those in the vicinity are
Brought ME to connect to this attacker's station. If the IMSI number of the person to be intercepted is not yet known, it must first be identified from the multitude of telephone calls made in the area. Professional devices such as the GA-901 from “Rohde & Schwarz” can therefore record several channels at the same time. This means that uninvolved people can also be eavesdropped. With this method, only outgoing phone calls can be eavesdropped. The outgoing call is forwarded to a "real" BTS. The so-called "MITM impersonation" uses the "Dynamic SIM cloning" method to position oneself in the uplink and also in the downlink channel between the communication partners. An "IMSI request" prompts the handset to disclose this unique number, which rarely occurs in normal operation. This allows movement profiles to be created, although this is to be prevented by the TMSI.

IMSI catchers are mainly used by law enforcement agencies and intelligence services to determine the locations and to create a movement profile of certain people.

=== Encryption ===

The encryption algorithm A5 is used on the air interface between the ME and the BTS. When A5 / 1 and A5 / 2 were developed in the late 1980s, the decision was made to use "Security By Obscurity", which is to say that the security of the process depends on the algorithm being kept secret. By 1999, both stream cipher methods were investigated by Marc Briceno and other scientists using reverse engineering and finally published.
An attack on A5 / 1 was carried out by A. Biryukov, A. Shamir, and D. Wagner in 2000. The complexity of the original 264 has been reduced to 238 and 248 respectively. In the meantime, “Rainbow Tables” 15, 16 are used to decrypt the A5 / 1. This technology shortens the computational effort in order to calculate back the correct session key, with which it is then possible to passively listen in on phone calls in real time. A modified cell phone of an older design is completely sufficient for this. A5 / 1 is used in Europe and the USA. The much weaker A5 / 2 was developed for countries where strong encryption is prohibited. According to the standardization committee, this algorithm has not been allowed to be used since 2007.
With UMTS, only A5 / 3 is used to encrypt the radio connection. Also known as KASUMI, the procedure was published in 2002. However, more security is only created by the increased complexity of the block cipher procedure. In the GSM network sections between BTS, BSC and MSC, the data is not encrypted and is transmitted via radio link if required, which means that passive eavesdropping or the interception of the session key is possible at these points.
An up-to-date overview of the security level of those in use: The GSM-MAP project is intended to enable cellular networks. The website shows Osmocom-compatible mobile phones and laptops, which are visualized on a map.
Link: https://gsmmap.org

== References ==

* https://de.wikipedia.org/wiki/A5_(Algorithmus)
* https://it-forensik.fiw.hs-wismar.de/index.php/IMSI-Catcher
* https://www.tarife.at/wissen/imsi-catcher
* https://www.heise.de/newsticker/meldung/26C3-GSM-Hacken-leicht-gemacht-892911.html
* https://www.webcitation.org/5rgp2JlUf
* https://gsmmap.org

[[Category:Documentation]]