6 ms·

> Sender can be spoofed Is this worldwide or US? I for now trust the senderid and assume them to be valid if they are coming from bank etc. I also haven't hear

> Sender can be spoofed Is this worldwide or US? I for now trust the senderid and assume them to be valid if they are coming from bank etc. I also haven't heard of anyone spoofing SMS. Should I be more cautious?

Aaargh20318 6y ago
> Is this worldwide or US? Worldwide. SMS is just like e-mail, you can put anything you want in the sender field. You should absolutely not trust SMS.
- mrtksn 6y ago
  Any idea on the extra security measures? In Turkey for example, when you change your SIM card the 2FA from the banks will stop working and you need to call your bank to re-activate it. That of course seems like a measure to prevent SIM cloning but maybe there are some security protections against spoofing. In many places SMS is a popular way to do payments and 2FA for high security applications.
  - rincebrain 6y ago
    Where does SMS get used to do payments? (...and how?) SMS for 2FA is known to be a very bad idea, and some security experts have been shouting about the need to stop doing that for a while. I also can't see any country managing to implement more restrictions on SMS without either breaking a lot of "legitimate" sources of SMS or being ineffective outside of a very narrow window (e.g. only blocking forged SMS for numbers originating within one country)
    - e3bc54b2 6y ago
      > Where does SMS get used to do payments? (...and how?) In India, for every card transaction, for every DMAT transaction, for every password/PIN change SMS is used as 2FA. It is also mandated to require SMS 2FA for every one of these cases. If my bank has any means to use TOTP/Yubikey, it is absolutely not made obvious, led alone clear or even possible.
      - rincebrain 6y ago
        Okay, so SMS gets used as 2FA for all those things, not somehow a primary method of creating transactions, correct? Unfortunately, quickly looking, [1] suggests at least one of the listed services for sending arbitrarily forged SMS messages explicitly works in India, so it seems like this is still true for you. :( [1] - https://www.usethistip.com/5-websites-to-send-anonymous-or-fake-sms.html https://www.usethistip.com/5-websites-to-send-anonymous-or-f...
    - lucb1e 6y ago
      "Where?!" Everywhere. It's being phased out in many places, but as a rule of thumb, mostly everywhere still. "known to be very bad ... been shouting ..." Right, yeah, to put it in some perspective remember that you're talking second factor here. This is not your login, this is a secondary confirmation and you still need some serious motivation to bypass it. It's definitely doable, I work in security and I know what kind of attacks you're thinking of, but it's not the opportunistic kind of thing that a common thief will do without technical research and planning it out. If you know how to do it, you can probably find better jobs than this. It also doesn't scale well because you can only use it on people whose bank login you've already cracked in the first place.
      - rincebrain 6y ago
        I'd never seen or heard of it being used for payments before, which is why I asked - I'd heard of phone numbers being used as account names (effectively) in some payment systems, but being involved in the workflow of making payments is entirely novel to me. I'm aware it's not your login, but it feels the same as asking someone for publicly searchable information to "verify your identity" - an additional "security" step that doesn't actually slow down any attacker more dedicated than a passing whim, but makes people feel good about whoever is using it, when there are better options that don't have the problems of SMS. Yes, it doesn't scale well to bulk attacking, but most of my interactions are with people who take reasonable precautions like keeping their machines patched, not installing random crap from the internet, and generally avoiding other fun ways people get swept up in low-hanging fruit campaigns. SMS 2FA is better than no 2FA at all, it's just frustrating to watch many companies deploy it and go home when there are better options, some of which solely also require a phone. edited to correct my statement: I originally said "SMS 2FA is better than no 2FA at all in a number of cases", but no, I'm pretty confident it's strictly better, even with all my laments about it.
        dividedbyzero 6y ago
        What better options are there that have approximately the same ease of use? SMS works with every conceivable phone, even most landlines if need be, users don't have to install a separate authenticator app, which may require a Google/iCloud password (now where did I put that post-it note?), that takes up space that may be scarce on low-end phones and that may not even be compatible with very old phones, leaving affected people in a really unsatisfactory spot. Then they need to set up codes for every login, figure out how to switch back and forth between apps and how to copy codes, which is not very discoverable at least in Google Authenticator – most people seem to memorize and type instead, cumbersome. Hardware tokens are even worse, people misplace those a lot and unless you are a bank with a mature process for issuing these, setup is probably even more of a hassle. All of this may be big deal if you (also) target less technical people and want them to use your product when they have the option not to. With SMS, all the user needs is a phone number. Pretty much everyone is familiar with that, most will readily share it, too. iOS will even extract codes and show them on top of the keyboard, just wait a second or two and tap the code, done. It's about as painless and frictionless as it can reasonably be, with apparently relatively inconsequential security drawbacks – given it's supposedly trivial to fake SMS, there don't seem to be a lot of people doing so at scale. Maybe a breach like this one will finally change that? Remains to be seen. For now I can totally see why one might stick with SMS as a second factor.
    - CaptainZapp 6y ago
      > Where does SMS get used to do payments? (...and how?) Look up M-Pesa[1]. Which is a hugely successful, mobile phone based payment system in multiple countries. In Kenya alone, where it started, it had 17Million subscribers. In 2011, that was. [1] https://en.wikipedia.org/wiki/M-Pesa https://en.wikipedia.org/wiki/M-Pesa
  - Nextgrid 6y ago
    Carriers can indeed expose APIs for banks and other third-parties to check if a SIM has recently been reissued, but that's a separate problem from spoofing.
- 74d-fe6-2c6 6y ago
  Are there Android apps for that?
  - v1nc 6y ago
    Hushsms is one, but requires Xposed Framework.
    - NavinF 6y ago
      Does that let you spoof sender address on any phone? I was under the impression that you had to create an account with a SIP provide to do that. (Btw a Google search for "Hushsms" results in shady/cancerous app stores that all seem to mirror each other. Where is the official website/thread?)
  - escalt 6y ago
    I'm absolutely no expert on this, but I think your provider would usually filter this spoofing attempt out, just like with IP spoofing. But if you're in the right spot in the network (e.g. your provider doesn't check for spoofing or you're your own "provider") you can do whatever you want. Another problem with Android could be that the operating system might not have enough control over the SIM-Card/Modem to spoof phone numbers. I have heard about people using some services to send/call from spoofed numbers though
- lmilcin 6y ago
  Actually, I trust e-mail more than SMS. With e-mail at least you can look at the headers and if you know which part you can trust you can verify where it came from. With SMS there is no such possibility.
- prower 6y ago
  I'm pretty sure Italy requires a company to register to an official list before being able to put a personalized sender ID in your SMS communications. I'm not sure about the inner workings but seems far from "whatever you want". I kinda assumed this was a widespread modus operandi, apparently it's not?
smcleod 6y ago
Absolutely do not trust the SMS sender name or message content in any country. SMS can be spoofed so easily anyone can do it.
- tokamak-teapot 6y ago
  I can confirm this happens in the UK.
cosmodisk 6y ago
We heavily use programmatic SMS sending at work. There are two options how it could appear on the recipient's end: as a normal phone number, to which you can reply,etc. We had to purchase a dedicated number for this. The other option is to simply put whatever sender ID you want- we use company name.This way you can't reply to the message,so we mainly use it for marketing purposes. Nothing stops me from replacing <company_name> with <random_number_belonging_to_bank>
sbarre 6y ago
Never trust caller ID or senderid on phone calls or SMS. The reason is that phone companies interoperate grudgingly and do the minimum required to pass calls and messages between each other, and also most phone companies are 100+ year old companies who have just layered modern tech on top of their old stuff. They handle a massive unending stream of calls/messages and they can't possibly validate each one (even if they wanted to), so when a call comes into your provider (mobile or land line) it comes with all the metadata fields (sender, etc) populated, and your provider just passes that along without any verification. This was less of a problem with there was a reasonably limited number of phone companies (a few per country) and they were all large enterprises.. Now with the rise of Twilio and tons of other pay-as-you-go companies that can hook into the global phone network to send calls and messages, and MVNOs (virtual phone companies that sit on top of the incumbent ones), there are too many players to track and in the name of convenience (and cost-savings) we haven't kept up with the verification part of the chain.
- pbhjpbhj 6y ago
  >they can't possibly validate each one // Why not? They don't pass on all metadata, that's part of the problem. If a call originates in $foreign_country, the sender gets to spoof it as a local call (sometimes they even use your own phone number). Are you really telling me there's no way to tell the difference between an off-shore call and a local one. It seems if this were true that billing is impossible, yet somehow the origin gets billed (though admittedly that might only be the immediate upstream, but usually this will be enough to disambiguate a scam call). Phone companies make money from scammers. It doesn't seem to be a technical bar, rather a financial disinclination that stops phone companies from robust action.
  - qilo 6y ago
    There are valid use cases for spoofing caller ID. It’s been a long time since I dabbled with Asterisk (IP PBX), IIRC, by default the call forwarding/redirection function uses metadata from the original incoming call. Let’s say, you’ve programmed your PBX that after 30 seconds of incoming call ringing, you want to redirect/forward the call (that is to make a new leg, and then connect them together) to your mobile phone number. I’m pretty sure, on your mobile phone you’d want to see the original caller’s number for incoming call, not the PBX’s phone number.
misnome 6y ago
This is probably overkill to say but to be sure: Never trust any information from SMS, or from a telephone call (or email) - both SMS and CallerID can both be trivially spoofed, and frequently are. If they have e.g. found out what bank you use, they can make the number look like it came from your bank ("See, this number is listed on the back of your card" is a common approach) If you get a call or SMS requiring followup, then look/ask for a reference number and a publicly listed number you can call back on - _and verify this number is listed on the organisation website before calling_, ideally on a telephone you know they can't "hold the line open" on (less of a problem now people mostly don't have landlines). It's okay to "engage" with a caller as long as you are careful to not give up any personal information - especially in cases where it's a bank they should be fine with you refusing security until you can call back. Don't ever relay information between channels e.g. if you _think_ you are talking to the bank, don't relay the contents of a 2-factor SMS you get, even if they say they are "sending" one to you. There have been cases where scammers have called the bank at the same time as calling the mark, so that when the scamee called the bank on a different line the bank verified that "they" were on another line. In reflection, it's kind of crazy the things you have to be suspicious/paranoid and aware of, I'm not surprised that even competent/intelligent people get scammed, it often seems that the infrastructure that we rely on for trust is even flimsier than you could imagine. Probably there are more extreme cases where these general rules aren't enough but probably unless you are a big CEO or something you are below the targeting threshold (see e.g. https://nakedsecurity.sophos.com/2019/09/05/scammers-deepfake-ceos-voice-to-talk-underling-into-243000-transfer/ https://nakedsecurity.sophos.com/2019/09/05/scammers-deepfak... which will probably only become easier over time). A healthy skepticism about complicated workflows is probably helpful.

Aaargh20318 6y ago

> Is this worldwide or US? Worldwide. SMS is just like e-mail, you can put anything you want in the sender field. You should absolutely not trust SMS.

mrtksn 6y ago
Any idea on the extra security measures? In Turkey for example, when you change your SIM card the 2FA from the banks will stop working and you need to call your bank to re-activate it. That of course seems like a measure to prevent SIM cloning but maybe there are some security protections against spoofing. In many places SMS is a popular way to do payments and 2FA for high security applications.
- rincebrain 6y ago
  Where does SMS get used to do payments? (...and how?) SMS for 2FA is known to be a very bad idea, and some security experts have been shouting about the need to stop doing that for a while. I also can't see any country managing to implement more restrictions on SMS without either breaking a lot of "legitimate" sources of SMS or being ineffective outside of a very narrow window (e.g. only blocking forged SMS for numbers originating within one country)
  - e3bc54b2 6y ago
    > Where does SMS get used to do payments? (...and how?) In India, for every card transaction, for every DMAT transaction, for every password/PIN change SMS is used as 2FA. It is also mandated to require SMS 2FA for every one of these cases. If my bank has any means to use TOTP/Yubikey, it is absolutely not made obvious, led alone clear or even possible.
    - rincebrain 6y ago
      Okay, so SMS gets used as 2FA for all those things, not somehow a primary method of creating transactions, correct? Unfortunately, quickly looking, [1] suggests at least one of the listed services for sending arbitrarily forged SMS messages explicitly works in India, so it seems like this is still true for you. :( [1] - https://www.usethistip.com/5-websites-to-send-anonymous-or-fake-sms.html https://www.usethistip.com/5-websites-to-send-anonymous-or-f...
  - lucb1e 6y ago
    "Where?!" Everywhere. It's being phased out in many places, but as a rule of thumb, mostly everywhere still. "known to be very bad ... been shouting ..." Right, yeah, to put it in some perspective remember that you're talking second factor here. This is not your login, this is a secondary confirmation and you still need some serious motivation to bypass it. It's definitely doable, I work in security and I know what kind of attacks you're thinking of, but it's not the opportunistic kind of thing that a common thief will do without technical research and planning it out. If you know how to do it, you can probably find better jobs than this. It also doesn't scale well because you can only use it on people whose bank login you've already cracked in the first place.
    - rincebrain 6y ago
      I'd never seen or heard of it being used for payments before, which is why I asked - I'd heard of phone numbers being used as account names (effectively) in some payment systems, but being involved in the workflow of making payments is entirely novel to me. I'm aware it's not your login, but it feels the same as asking someone for publicly searchable information to "verify your identity" - an additional "security" step that doesn't actually slow down any attacker more dedicated than a passing whim, but makes people feel good about whoever is using it, when there are better options that don't have the problems of SMS. Yes, it doesn't scale well to bulk attacking, but most of my interactions are with people who take reasonable precautions like keeping their machines patched, not installing random crap from the internet, and generally avoiding other fun ways people get swept up in low-hanging fruit campaigns. SMS 2FA is better than no 2FA at all, it's just frustrating to watch many companies deploy it and go home when there are better options, some of which solely also require a phone. edited to correct my statement: I originally said "SMS 2FA is better than no 2FA at all in a number of cases", but no, I'm pretty confident it's strictly better, even with all my laments about it.
      - dividedbyzero 6y ago
        What better options are there that have approximately the same ease of use? SMS works with every conceivable phone, even most landlines if need be, users don't have to install a separate authenticator app, which may require a Google/iCloud password (now where did I put that post-it note?), that takes up space that may be scarce on low-end phones and that may not even be compatible with very old phones, leaving affected people in a really unsatisfactory spot. Then they need to set up codes for every login, figure out how to switch back and forth between apps and how to copy codes, which is not very discoverable at least in Google Authenticator – most people seem to memorize and type instead, cumbersome. Hardware tokens are even worse, people misplace those a lot and unless you are a bank with a mature process for issuing these, setup is probably even more of a hassle. All of this may be big deal if you (also) target less technical people and want them to use your product when they have the option not to. With SMS, all the user needs is a phone number. Pretty much everyone is familiar with that, most will readily share it, too. iOS will even extract codes and show them on top of the keyboard, just wait a second or two and tap the code, done. It's about as painless and frictionless as it can reasonably be, with apparently relatively inconsequential security drawbacks – given it's supposedly trivial to fake SMS, there don't seem to be a lot of people doing so at scale. Maybe a breach like this one will finally change that? Remains to be seen. For now I can totally see why one might stick with SMS as a second factor.
  - CaptainZapp 6y ago
    > Where does SMS get used to do payments? (...and how?) Look up M-Pesa[1]. Which is a hugely successful, mobile phone based payment system in multiple countries. In Kenya alone, where it started, it had 17Million subscribers. In 2011, that was. [1] https://en.wikipedia.org/wiki/M-Pesa https://en.wikipedia.org/wiki/M-Pesa
- Nextgrid 6y ago
  Carriers can indeed expose APIs for banks and other third-parties to check if a SIM has recently been reissued, but that's a separate problem from spoofing.
74d-fe6-2c6 6y ago
Are there Android apps for that?
- v1nc 6y ago
  Hushsms is one, but requires Xposed Framework.
  - NavinF 6y ago
    Does that let you spoof sender address on any phone? I was under the impression that you had to create an account with a SIP provide to do that. (Btw a Google search for "Hushsms" results in shady/cancerous app stores that all seem to mirror each other. Where is the official website/thread?)
- escalt 6y ago
  I'm absolutely no expert on this, but I think your provider would usually filter this spoofing attempt out, just like with IP spoofing. But if you're in the right spot in the network (e.g. your provider doesn't check for spoofing or you're your own "provider") you can do whatever you want. Another problem with Android could be that the operating system might not have enough control over the SIM-Card/Modem to spoof phone numbers. I have heard about people using some services to send/call from spoofed numbers though
lmilcin 6y ago
Actually, I trust e-mail more than SMS. With e-mail at least you can look at the headers and if you know which part you can trust you can verify where it came from. With SMS there is no such possibility.
prower 6y ago
I'm pretty sure Italy requires a company to register to an official list before being able to put a personalized sender ID in your SMS communications. I'm not sure about the inner workings but seems far from "whatever you want". I kinda assumed this was a widespread modus operandi, apparently it's not?

smcleod 6y ago

Absolutely do not trust the SMS sender name or message content in any country. SMS can be spoofed so easily anyone can do it.

tokamak-teapot 6y ago
I can confirm this happens in the UK.

cosmodisk 6y ago

We heavily use programmatic SMS sending at work. There are two options how it could appear on the recipient's end: as a normal phone number, to which you can reply,etc. We had to purchase a dedicated number for this. The other option is to simply put whatever sender ID you want- we use company name.This way you can't reply to the message,so we mainly use it for marketing purposes. Nothing stops me from replacing <company_name> with <random_number_belonging_to_bank>

sbarre 6y ago

Never trust caller ID or senderid on phone calls or SMS. The reason is that phone companies interoperate grudgingly and do the minimum required to pass calls and messages between each other, and also most phone companies are 100+ year old companies who have just layered modern tech on top of their old stuff. They handle a massive unending stream of calls/messages and they can't possibly validate each one (even if they wanted to), so when a call comes into your provider (mobile or land line) it comes with all the metadata fields (sender, etc) populated, and your provider just passes that along without any verification. This was less of a problem with there was a reasonably limited number of phone companies (a few per country) and they were all large enterprises.. Now with the rise of Twilio and tons of other pay-as-you-go companies that can hook into the global phone network to send calls and messages, and MVNOs (virtual phone companies that sit on top of the incumbent ones), there are too many players to track and in the name of convenience (and cost-savings) we haven't kept up with the verification part of the chain.

pbhjpbhj 6y ago
>they can't possibly validate each one // Why not? They don't pass on all metadata, that's part of the problem. If a call originates in $foreign_country, the sender gets to spoof it as a local call (sometimes they even use your own phone number). Are you really telling me there's no way to tell the difference between an off-shore call and a local one. It seems if this were true that billing is impossible, yet somehow the origin gets billed (though admittedly that might only be the immediate upstream, but usually this will be enough to disambiguate a scam call). Phone companies make money from scammers. It doesn't seem to be a technical bar, rather a financial disinclination that stops phone companies from robust action.
- qilo 6y ago
  There are valid use cases for spoofing caller ID. It’s been a long time since I dabbled with Asterisk (IP PBX), IIRC, by default the call forwarding/redirection function uses metadata from the original incoming call. Let’s say, you’ve programmed your PBX that after 30 seconds of incoming call ringing, you want to redirect/forward the call (that is to make a new leg, and then connect them together) to your mobile phone number. I’m pretty sure, on your mobile phone you’d want to see the original caller’s number for incoming call, not the PBX’s phone number.

misnome 6y ago

This is probably overkill to say but to be sure: Never trust any information from SMS, or from a telephone call (or email) - both SMS and CallerID can both be trivially spoofed, and frequently are. If they have e.g. found out what bank you use, they can make the number look like it came from your bank ("See, this number is listed on the back of your card" is a common approach) If you get a call or SMS requiring followup, then look/ask for a reference number and a publicly listed number you can call back on - _and verify this number is listed on the organisation website before calling_, ideally on a telephone you know they can't "hold the line open" on (less of a problem now people mostly don't have landlines). It's okay to "engage" with a caller as long as you are careful to not give up any personal information - especially in cases where it's a bank they should be fine with you refusing security until you can call back. Don't ever relay information between channels e.g. if you _think_ you are talking to the bank, don't relay the contents of a 2-factor SMS you get, even if they say they are "sending" one to you. There have been cases where scammers have called the bank at the same time as calling the mark, so that when the scamee called the bank on a different line the bank verified that "they" were on another line. In reflection, it's kind of crazy the things you have to be suspicious/paranoid and aware of, I'm not surprised that even competent/intelligent people get scammed, it often seems that the infrastructure that we rely on for trust is even flimsier than you could imagine. Probably there are more extreme cases where these general rules aren't enough but probably unless you are a big CEO or something you are below the targeting threshold (see e.g. https://nakedsecurity.sophos.com/2019/09/05/scammers-deepfake-ceos-voice-to-talk-underling-into-243000-transfer/ https://nakedsecurity.sophos.com/2019/09/05/scammers-deepfak... which will probably only become easier over time). A healthy skepticism about complicated workflows is probably helpful.