More specifically, here at bsdly.net we've been seeing attempts at logging in to the pop3 mail retrieval service using usernames that sound distinctively like Chinese names, and the attempts originate almost exclusively from Chinese networks.
This table lists the user names and corresponding real life names attempted so far:
|Song Song Jun||songsongjun|
|Tang Tang Jun||tangtangjun|
That list of some 493 names is up to date as of this writing, 2016-08-23 early evening CEST. A few more turn up with the bursts of activity we have seen every day since June 19th, 2016.
A possibly more up to date list is available here. That's a .csv file, if that sounds unfamiliar, think of it as a platform neutral text representation (to wit, "Comma Separated Values") of a spreadsheet or database -- take a peek with Notepad.exe or similar if you're not sure. I'll be updating that second list along with other related data at quasi-random intervals as time allows and as long as interesting entries keep turning up in my logs.
If your name or username is on either of those lists, you would be well advised to change your passwords right now and to check breach notification sites such as Troy Hunt's haveibeenpwned.com or breachalarm.com for clues to where your accounts could have been compromised.
That's your scoop for now. If you're interested in some more background and data, keep reading.
If you are a regular or returning reader of this column, you are most likely aware that I am a Unix sysadmin. In addition to operating and maintaining variuos systems in my employers' care, I run a small set of servers of my own that run a few Internet-facing services for myself and a small circle of friends and family.
For the most part those systems are roundly ignored by the world at large, but when they are not, funny, bizarre or interesting things happen. And mundane activities like these sometimes have interesting byproducts. When you run a mail service, you are bound to find a way to handle the spam people will try to send, and about ten years ago I started publishing a blacklist of known spamming hosts, generated from attempts to deliver mail to a slowly expanding list of known bad, invalid, never to be deliverable addresses in the domains we handle mail for.
After a while, I discovered that the list of spamtrap addresses (once again, invalid and destined never to be deliverable, ever) had been hilariously repurposed: The local parts (the string before the @ or 'at sign') started turning up as usernames in failed attempts to log on to our pop3 mail retrieval service. That was enough fun to watch that I wrote that article, and for reasons known only to the operators of the machines at the other end, those attempts have never stopped entirely.
These attempts to log in as our imaginary friends is a strong contender for the most bizarre and useless activity ever, but when those attempts were no longer news, there was nothing to write about. The spamtrap login attempts make up sort of a background noise in the authentication logs, and whenever there is an attempt to log in as a valid user from somewhere that user is clearly not, the result is usually that an entire network (whatever I could figure out from whois output) would be blocked from any communication with our site for 24 hours.
There are of course also attempts to log in as postmaster, webmaster and other IDs, some RFC mandated, that most sites including this one would handle as aliases to make up the rest of the background noise.
Then recently, something new happened. The first burst looked like this in my logs (times given in local timezone, CEST at the time):
Jun 19 06:14:58 skapet spop3d: authentication failed: no such user: lilei - 18.104.22.168
Jun 19 06:15:01 skapet spop3d: authentication failed: no such user: lilei - 22.214.171.124
Jun 19 06:15:03 skapet spop3d: authentication failed: no such user: lilei - 126.96.36.199
-- and so on, for a total of 78 attempts to log in as the non-existing user lilei, in the space of about five minutes. A little later, a similar burst of activity came for the user name lika:
Jun 19 14:11:30 skapet spop3d: authentication failed: no such user: lika - 188.8.131.52
Jun 19 14:12:22 skapet spop3d: authentication failed: no such user: lika - 184.108.40.206
Jun 19 14:12:26 skapet spop3d: authentication failed: no such user: lika - 220.127.116.11
Jun 19 14:12:30 skapet spop3d: authentication failed: no such user: lika - 18.104.22.168
and so on, for a total of 76 attempts. Over the next few days I noticed an uptick in failed pop3 access attempts that were not for valid users and did not match any entry on our spamtraps list. Still, those attempts were for users that do not exist, and would produce no useful result so I did not do anything much about them.
It was only during the early weeks of July that it struck me that the user name attempted here
Jul 8 12:19:08 skapet spop3d: authentication failed: no such user: lixing - 22.214.171.124
Jul 8 12:19:28 skapet spop3d: authentication failed: no such user: lixing - 126.96.36.199
Jul 8 12:19:37 skapet spop3d: authentication failed: no such user: lixing - 188.8.131.52
Jul 8 12:19:49 skapet spop3d: authentication failed: no such user: lixing - 184.108.40.206
(a total of 54 attempts for that user name) might actually be based on the name of a Chinese person. "Li Xing" sounded plausible enough as a possible real person. It's perhaps worth noting that at the time I had just finished reading the first two volumes of Cixin Liu's The Three Body Problem, so I was a bit more in tune than usual with what could be plausible Chinese names than I had been. (And yes, the books are very much to my taste and I have the yet unpublished translation of the third volume on pre-order.)
Unsurprisingly, a quick whois lookup revealed that the machines that tried reading the hypothetical person Li Xing's mail all had IP addresses that belonged to Chinese networks.
Once I realized I might be on to a new pattern, I went back over a few days' worth of failed pop3 login attempts and found more than a handful of usernames that looked like they could be based on Chinese names. Checking the whois data for the IP addresses in those attempts, all turned out to be from Chinese networks.
That was in itself an interesting realization, but a small, random sample does not make for proof. In order to establish an actual data set, it was back to collecting data and analysing the content.
First, collect all log data on failed pop3 attempts for a long enough period that we have a reasonable baseline and can distinguish between the background noise and new, exciting developements.
The file bigauthlog is that collection of data. Digging through my archives going back in time, I stopped at January 16, 2016 for no other reason than this would be roughly six months' worth of data, probably enough to give a reasonable baseline and to spot anomalies.
If you've read the previous columns, you will be familiar with the scripts that produce various text and CSV reports from log data input: A text report of user names by number of access attempts, a CSV dump of the same, with first and last spotted, a text report of hosts attempting access, sorted by number of attempts, a CSV dump of the same, with first and last seen dates as for the user names.
But what I wanted to see was where the login attempts were coming from for which usernames, so I started extracting the unique host to username mappings. For each entry in this CSV file, there is a host and a user name it has tried at least once (if you import that somewhere, make sure you mark the Username column as text -- LibreOffice Calc at least becomes confused when trying to parse some of those strings). The data also records whether that particular username was part of the spamtrap database at the time. If you want to do that particular check on your own greytrapping database, any matching output from
$ doas spamdb | grep -i username@
on your greytrapper box will mean it is in your list. And then finally for each entry there is the expected extract from available whois info: network address range, the network name and the country.
The most useful thing to do with that little database is to play with sorting on various fields and field combinations. If you sort on the "In spamtraps" field, the supposed Chinese names turn up with "No"s, along with a few more random-seeming combinations.
While I was building the data set I decided to add those new usernames with @bsdly.net appended to the spamtraps, and this is what finally pushed the number of spamtraps past the 30,000 mark.
Just browsing the data or perhaps sorting by IP address will show you that the pop3 gropers are spread across a large number of networks in a number of countries and territories with numbers roughly in proportion to the size of that country or territory's economy. Some, such as a particular Mexican ISP and cable TV operator stand out as being slightly over-represented, and as expected networks in the US and China stand for a large number of the total.
If you sort on the In spamtraps field, you will see that a large number of the entries that were not in the spamtraps are the ones identified as Chinese personal names, but not all. Some of the No entries are the RFC mandated mailboxes, some are aliases that are in use here for other reasons, and finally more than a handful that would fit the general description of the rest of the spamtraps: Strings superficially resembling personal names or simply random strings. These may be parts of the potential spamtraps I missed while fishing spamtrap candidates out of logfiles some time over the decade of weirdness that has gone into maintaining the spamtraps list.
But if you sort the data primarily on the fields Name, Country, and if you like IP address and User name, you will see that as anticipated the attempts on Chinese-sounding user names come exclusively from Chinese networks, except only the "Fa Dum" (fadum) user, which appears to have been attempted only twice (on June 6th) from an IP address registered in the USA and may very well be a misclassification on my part. That particular sorting, with duplicates removed, is the origin of the list of names and usernames given earlier in this article and this CSV file.
Now that we have established that the attempts at Chinese user names come exclusively from Chinese networks, the next questions become: Who are the cyber criminals behind this activity, and what are their motivations? And why are they bothering with hosts in faraway Europe to begin with?
For the first question, it is hard to tell from this perch, but whoever runs those attempts apparently have the run of large swathes of network real estate and seem to not take any special care not to be detected, other than of course distributing the attempts widely across the network ranges and coming in only in short bursts.
So are those attempts by, let us say the public sector, to steal political dissidents' email? Or perhaps, still with a public sector slant, simply hunting for any and all overseas assets belonging to Chinese nationals? Or are we simply seeing the activities of Chinese private sector cyber criminals who are trying out likely user names wherever they can find a service that listens?
Any of all of these things could be true, but in any case it's not unlikely that what we are seeing somebody trying to find new places where username and password combinations from a recent breach might work. After all, username and password combinations that have been verified to work somewhere are likely worth more on the market than the unverified ones.
Looking at the log entries, there are sequences there that could plausibly have been produced by humans typing at keyboards. Imagine if you please vast, badly lit and insufficiently ventilated Asian cyber-sweatshops, but I would not be too surprised to find that this is actually a highly automated operation, with timing tuned to avoid detection.
Security professionals have been recommending that people stop using the pop3 protocol since as long as I care to remember, but typing "pop3" into shodan.io still produces a whopping 684,291 results, meaning that the pop3 service is nowhere near as extinct as some would have preferred.
The large number of possible targets is a likely explanation for the burstiness of the activity we are seeing: with that many hosts to cover, the groping hosts will need to set up some sort of rotation, and in addition there is the need to stay below some volume of traffic per host in order to avoid detection. This means that what any one site sees is only a very small part of the total activity. The pop3 hunt for Chinese users is most likely not exclusive to the fjord country.
If you run a pop3 service, please do yourself a favor and check your setup for any weaknesses including any not yet applied updates, as you were about to do anyway. Once you've done that, take some moments to browse your logs for strange looking login attempts.
If you find something similar to what I've reported here, I would like to hear from you. Please note that at least one of the pop3 deaemons out there by default does not report the username for failed authentication attempts but notes that the username was unknown instead. Anyway, your war stories will be appreciated in email or comments.
If your name or username appears in the table at the start of this article or in this CSV file, please start checking for unusual activity involving your accounts and start changing passwords right away. Ask your service providers if they offer more secure alternatives, and if they do, consider using these alternatives. And as I mentioned earlier, do check breach notification sites such as haveibeenpwned.com or breachalarm.com for clues to help find out whether your data could be at risk in any of the services you do use. And of course, feedback in comments or email is welcome.
And finally, if you have information on one or more breaches that may have been the source of this list of likely Chinese user names, I'd like to hear from you too.
Good night and good luck.
I would like to thank Tore Nordstrand and Øystein Alsaker for valuable input on various aspects of this article.
The data referenced in this article will likely be updated on a roughly daily basis while the Chinese episode lasts. You can fetch them from the links in the article or from this directory, which also contains some trivial data extraction and data massaging scripts I use. If you find any errors or have any concerns, please let me know.