2018-06-19 I don't run your nameserver 2 days ago
Showing in the logs since a few hours:Jun 18 12:48:36 server named[16424]: client 92.247.148.230#38664: query '1.3.20.172.in-addr.arpa/PTR/IN' denied Jun 18 12:48:39 server named[16424]: client 92.247.148.230#38664: query '14.0.20.172.in-addr.arpa/PTR/IN' denied Jun 18 12:48:45 server named[16424]: client 92.247.148.230#38664: query '41.1.20.172.in-addr.arpa/PTR/IN' denied Jun 18 12:48:47 server named[16424]: client 92.247.148.230#38664: query '6.1.20.172.in-addr.arpa/PTR/IN' deniedGiven earlier reports of the same IPv4 address asking about the same queries this has been seen by at least one other place before. Blacklisted for now, maybe I can think of some answers that can slow down the resolver later.
2018-05-22 The linkspammers are back, but they are trying to hide it a lot better 1 month ago
Over the years I have ranted several times about linkspammers. About spammers in general too, but linkspammers are a special category. Most of them, especially the fully automated ones died when google started detecting their deceit. That time there was some amusement to be had reading mails "somehow there is an evil link to my site from your site, please remove it as it affects both our google ranking". But now they are back, but trying to hide it a lot better. I received several nicey-nicey and helpful mails with really personal suggestions to improve my site, or improve the world in general by adding some link they proposed, complete with the right anchor text. At first I thought they were personal and answered them telling them the proposed links were wrong, or they had not read the article/post/.. they wanted to change very carefully. And then a week or two later I'd get another personal mail asking whether I had considered their previous request. And answering with "did you read my answer?" did not change a thing. My best guess at the moment is that I wasn't looking at a personal mail and that I should add a lot of airquotes about terms like "personal" above. It's a template with 'page X' 'needs link Y' and 'with anchor text Z' and there is software running that checks whether page X has the 'right' link and keeps sending reminders until it does. As you can imagine (or not), I feel very annoyed by this new scam tactic. One sample:Hi pal, My name is Oliver and I'm writing to share an infographic that aims to educate people about PTSD amongst our veterans and serving military personnel. The infographic is titled "The Silent Enemy: How PTSD Damages Our Soldiers". You can view the infographic by clicking here: [link] To spread the word about these issues, I ask if you could add a "weblink" to this infographic from this page on your own website: https://idefix.net/~koos/newsitem.cgi/1318581406 Note how this page has only a link to 'military' but actually reading it for 4 seconds would let you know that it has no link to PTSD in the military. I chose this page because you already link to www.af.mil/News/Photos/ from this page. If this is possible, you could add the below text to this page on your own websi te: The Silent Enemy: How PTSD Damages Our Soldiers – An infographic aiming to raise awareness about PTSD in the military. Alternatively, you could also publish the infographic on your website as a "guest blog post". If this is OK, I can write a unique introduction to go with the infographic. This will save you time and also help to highlight the important issues covered in the infographic. I really appreciate your time. I know that linking to this infographic will help to build awareness about mental health issues amongst veterans and serving memb ers of the military. I'm sure this is a cause you would like to get behind by adding the above link. I've actually attached the infographic to this email for you to add to your website at either the page I suggest or as a fresh blog post. Many thanks, Oliver Clark Rehab 4 Alcoholism Please click on Unsubscribe to be unsubscribed from any future communications. P rivacy notice.The last line is quite a hint that this is from an automated system, the stories are somewhat long so this isn't always very visible. Now I also wonder whether the link would be to a very commercial rehab organisation.
2018-05-05 High-Tech Bridge 'security scan' causing big noise in the logs 1 month ago
I noticed a lot of error messages from sshd/imaps and other services all related to IPv4 address 192.175.111.254. Checking the firewall logs found even more attempts. It seems all this noise is related to a 'Web Server Security Test' from High-Tech Bridge. Something like the Qualys SSL Labs SSL Server Test but aimed at a complete test according to PCI DSS, HIPAA and NIST. Since most of those standards have to do with procedures too an automated test can never be complete. But with all these errors and firewall log entries it is very noisy. And now I wonder who was interested in my webserver security at a time that I was asleep.
2018-04-07 I'm glad you read my newsitem 2 months ago
Apr 6 23:41:16 greenblatt sshd[25116]: Invalid user squid from 139.99.122.129 Apr 7 01:44:09 greenblatt sshd[3495]: Invalid user squid from 110.10.189.108 Apr 7 08:21:37 greenblatt sshd[7106]: Invalid user squid from 118.24.100.11I'm glad you read my newsitem about keeping squid running.
2018-03-14 Try anything as an open webproxy 3 months ago
It seems any open port can be tried as an open webproxy. An open webproxy is interesting for hiding tracks or getting around restrictions. But some of the scans are getting stupid. There are still a lot of other tcp-based services, not everything is HTTP. From recent logs:Mar 14 13:46:42 greenblatt nnrpd[20297]: 185.100.87.248 unrecognized GET / HTTP/1.0 Mar 14 13:46:47 greenblatt nnrpd[20299]: 185.100.87.248 unrecognized OPTIONS / HTTP/1.0 Mar 14 13:46:52 greenblatt nnrpd[20301]: 185.100.87.248 unrecognized OPTIONS / RTSP/1.0And this gem of distributed scanning:Mar 8 08:45:00 greenblatt sm-mta[6355]: w287j0dE006355: 78.84.202.1.static.bjtelecom.net: probable open proxy: command=GET http://www.boxun.com/ HTTP/1.1\r\n Mar 8 08:45:00 greenblatt sm-mta[6359]: w287j0V0006359: [14.204.118.100]: probable open proxy: command=GET http://www.minghui.org/ HTTP/1.1\r\n Mar 8 08:45:00 greenblatt sm-mta[6360]: w287j0lM006360: [14.204.94.84]: probable open proxy: command=GET http://www.rfa.org/ HTTP/1.1\r\n Mar 8 08:45:04 greenblatt sm-mta[6353]: w287j4lq006353: [110.177.75.38]: probable open proxy: command=GET http://www.baidu.com/ HTTP/1.1\r\n Mar 8 08:45:04 greenblatt sm-mta[6356]: w287j4io006356: [101.249.104.160]: probable open proxy: command=GET http://www.bing.com/ HTTP/1.1\r\n Mar 8 08:45:04 greenblatt sm-mta[6357]: w287j4h0006357: [119.118.16.42]: probable open proxy: command=GET http://wujieliulan.com/ HTTP/1.1\r\n Mar 8 08:45:05 greenblatt sm-mta[6358]: w287j5pu006358: [112.66.106.4]: probable open proxy: command=CONNECT www.voanews.com:443 HTTP/1.0\r\n Mar 8 08:45:05 greenblatt sm-mta[6354]: w287j5bt006354: 36.49.239.221.broad.tj.tj.dynamic.163data.com.cn [221.239.49.36] (may be forged): probable open proxy: command=GET http://www.123cha.com/ HTTP/1.1\r\nInteresting timing and coordination on this one, looks like some form of central control was involved.
2018-03-05 Obfuscating powershell with -encoded and UTF-16 3 months ago
In some files I noticed a vbs file where I expected something else. Vbs sounds like visual basic script so I directly started looking for malware. And indeed I saw suspicous code, with a for me new type of obfuscation. The vbs has one really long line, beginning with:CreateObject("Wscript.Shell").Run("powershell -w hidden -ep bypass -enc aQBuAHYA bwBrAGUALQBlAHgAcAByAGUAcwBzAGkAbwBuACgAIgB7ADQAOAB9AHsAMQAyAH0AewAyADgAfQB7ADEA MAAzAH0AewAyADEAfQB7ADkAfQB7ADEAMAA2AH0AewA3ADAAfQB7ADIAOAB9AHsAOAB9AHsAMAB9AHsAand at the end:IgByACIALAAiAGsAIgAsACIAYQAiACwAIgAgACIALAAiAHYAIgAsACIAZwAiACwAIgBzACIALAAiAGUA IgAsACIAbgAiACwAIgArACIALAAiAHQAIgAsACIAcgAiACwAIgAiACwAIgB0ACIALAAiAHAAIgAsACIA ZQAiACwAIgBlACIALAAiAC8AIgAsACIAZQAiACwAIgBTACIAKQA=")Which looked very base64-like to me. But standard tools could not find out what it was:$ base64 -d < base64part | file - /dev/stdin: dataBut with a second look I could make out something:$ base64 -d < base64part | xxd | less 0000000: 6900 6e00 7600 6f00 6b00 6500 2d00 6500 i.n.v.o.k.e.-.e. 0000010: 7800 7000 7200 6500 7300 7300 6900 6f00 x.p.r.e.s.s.i.o. 0000020: 6e00 2800 2200 7b00 3400 3800 7d00 7b00 n.(.".{.4.8.}.{. 0000030: 3100 3200 7d00 7b00 3200 3800 7d00 7b00 1.2.}.{.2.8.}.{. 0000040: 3100 3000 3300 7d00 7b00 3200 3100 7d00 1.0.3.}.{.2.1.}. 0000050: 7b00 3900 7d00 7b00 3100 3000 3600 7d00 {.9.}.{.1.0.6.}. 0000060: 7b00 3700 3000 7d00 7b00 3200 3800 7d00 {.7.0.}.{.2.8.}. 0000070: 7b00 3800 7d00 7b00 3000 7d00 7b00 3200 {.8.}.{.0.}.{.2. 0000080: 7d00 7b00 3400 3100 7d00 7b00 3100 3100 }.{.4.1.}.{.1.1. 0000090: 3300 7d00 7b00 3600 3600 7d00 7b00 3000 3.}.{.6.6.}.{.0.Suddenly there is UTF-16 powershell code. Or when I simply cat it to a terminal:invoke-expression("{48}{12}{28}{103}{21}{9}{106}{70}{28}{8}{0}{2}{41}{113}{66} [..] -f "t","2"," ",".","i","f","C","'","c","o","2",")","n","n","0","c","'","/",It looks like some kind of array mapping, but I have no idea how to decode this into readable code to check what it does. I am quite sure it can't be up to any good if I keep finding levels of obfuscation!
2018-02-02 Trying to make me skip the rest of the security report 4 months ago
In the sshd logging today:sshd[26961]: Invalid user <!-- from 103.9.88.249But the logging is parsed via software that doesn't trust input either, so the rest is in the report too. Including more attempts from that IPv4 address.
2018-01-23 Avoiding the linux statefull firewall for some traffic 4 months ago
I was setting up a linux based firewall on a busy ntp server and to make sure everything worked as designed I added the usual:iptables -A INPUT -j ACCEPT --protocol all -m state --state ESTABLISHED,RELATEDAnd after less than half an hour the system log started filling withnf_conntrack: table full, dropping packet nf_conntrack: table full, dropping packet nf_conntrack: table full, dropping packet nf_conntrack: table full, dropping packetIt is indeed a busy server. The solution is to exclude all the ntp traffic from the stateful firewall. Which means I have to allow all kinds of ntp traffic (outgoing and incoming) by itself. The specific ruleset:iptables -t raw -A PREROUTING --protocol udp --dport 123 -j NOTRACK iptables -t raw -A OUTPUT --protocol udp --sport 123 -j NOTRACK iptables -A INPUT -j ACCEPT --protocol udp --destination-port 123I also made sure the rules for the ntp traffic are the first rules. Traffic at this server is somewhat over 1000 ntp request per second. So the counters of the NOTRACK rules go fast.# iptables -t raw -L -v Chain PREROUTING (policy ACCEPT 1652K packets, 126M bytes) pkts bytes target prot opt in out source destination 9635K 732M CT udp -- any any anywhere anywhere udp dpt:ntp NOTRACK 1650K 125M CT udp -- any any anywhere anywhere udp dpt:ntp NOTRACK Chain OUTPUT (policy ACCEPT 1522K packets, 117M bytes) pkts bytes target prot opt in out source destination 9029K 686M CT udp -- any any anywhere anywhere udp spt:ntp NOTRACK 1520K 116M CT udp -- any any anywhere anywhere udp spt:ntp NOTRACKBut no packets are dropped, which is good as this server is supposed to be under a constant DDoS.
2018-01-19 Collecting ages of ntpd mode 7 probes 5 months ago
I noticed today one of the ntp servers I manage has been collecting ages of ntpd mode 7 probes without ever responding. But it makes a nice overview of probing IPv4 addresses:remote address port local address count m ver rstr avgint lstint =============================================================================== 184.105.139.82 1714 xxx.xxx.xxx.xxx 3 7 2 1 3413098 40058 184.105.139.72 14152 xxx.xxx.xxx.xxx 7 6 2 1 1107023 60553 185.165.29.145 33482 xxx.xxx.xxx.xxx 9 7 2 1 647886 73704 91.200.12.126 47493 xxx.xxx.xxx.xxx 2 7 2 1 12199 78678 185.94.111.1 33066 xxx.xxx.xxx.xxx 44 7 2 1 139771 83493 212.237.45.33 39353 xxx.xxx.xxx.xxx 1 7 2 1 0 84058 184.105.139.122 16124 xxx.xxx.xxx.xxx 4 7 2 1 1830407 127241 165.227.44.214 36749 xxx.xxx.xxx.xxx 1 7 2 1 0 138342 185.82.203.150 38141 xxx.xxx.xxx.xxx 12 7 2 1 147806 143793 185.2.81.90 33119 xxx.xxx.xxx.xxx 6 7 2 1 199742 180842 184.105.139.110 57630 xxx.xxx.xxx.xxx 6 7 2 1 968029 223794 77.87.79.97 34540 xxx.xxx.xxx.xxx 2 7 2 1 31910 251316 184.105.139.102 50130 xxx.xxx.xxx.xxx 3 7 2 1 2950157 308291 185.55.218.227 33716 xxx.xxx.xxx.xxx 2 7 2 1 853413 311971 104.243.41.54 30820 xxx.xxx.xxx.xxx 2 7 2 1 3258925 334017 123.249.27.176 35963 xxx.xxx.xxx.xxx 7 7 2 1 452131 339518 191.96.249.173 42895 xxx.xxx.xxx.xxx 10 7 2 1 692139 348753 71.194.80.50 51096 xxx.xxx.xxx.xxx 2 7 2 1 74579 392665 184.105.139.126 38393 xxx.xxx.xxx.xxx 2 7 2 1 3535530 394349 185.55.218.250 48871 xxx.xxx.xxx.xxx 2 7 2 1 537671 411921 184.105.139.86 34651 xxx.xxx.xxx.xxx 5 7 2 1 1361673 478157 123.249.24.175 37973 xxx.xxx.xxx.xxx 6 7 2 1 476469 502270 184.105.139.98 21269 xxx.xxx.xxx.xxx 10 7 2 1 718112 567076 184.105.139.70 38190 xxx.xxx.xxx.xxx 6 7 2 1 1107237 649625 66.55.135.62 54536 xxx.xxx.xxx.xxx 8 7 2 1 40836 721372 138.197.130.148 39857 xxx.xxx.xxx.xxx 2 7 2 1 415601 788308 191.96.249.113 36079 xxx.xxx.xxx.xxx 2 7 2 1 1501700 862267 184.105.139.78 37702 xxx.xxx.xxx.xxx 4 7 2 1 1637431 908028 159.89.47.224 47766 xxx.xxx.xxx.xxx 5 7 2 1 361160 913255 162.209.168.12 39122 xxx.xxx.xxx.xxx 2 7 2 1 109901 976174 123.249.26.159 34990 xxx.xxx.xxx.xxx 41 7 2 1 88999 1045070 184.105.139.74 38666 xxx.xxx.xxx.xxx 6 7 2 1 822261 1079624 185.55.218.242 54815 xxx.xxx.xxx.xxx 7 7 2 1 89032 1102095 191.96.249.12 48406 xxx.xxx.xxx.xxx 4 7 2 1 1133779 1198815 101.100.146.139 39660 xxx.xxx.xxx.xxx 3 7 2 1 1951322 1244586 209.250.238.186 39459 xxx.xxx.xxx.xxx 2 7 2 1 53072 1252190 119.1.109.85 51099 xxx.xxx.xxx.xxx 10 7 2 1 223881 1325320 184.105.139.118 34319 xxx.xxx.xxx.xxx 4 7 2 1 905995 1339133 184.105.139.106 15081 xxx.xxx.xxx.xxx 2 7 2 1 2932231 1430316 191.96.249.131 35972 xxx.xxx.xxx.xxx 2 7 2 1 1499287 1491171 185.55.218.237 43409 xxx.xxx.xxx.xxx 2 7 2 1 4255207 1497992 185.55.218.236 55927 xxx.xxx.xxx.xxx 3 7 2 1 1566148 1718947 138.68.247.41 41914 xxx.xxx.xxx.xxx 2 7 2 1 53524 1936953 184.105.139.94 41523 xxx.xxx.xxx.xxx 5 7 2 1 1112720 1948506 45.63.27.150 40862 xxx.xxx.xxx.xxx 2 7 2 1 1676933 1991259 185.188.207.13 45915 xxx.xxx.xxx.xxx 20 7 2 1 156321 2041538 185.44.107.183 45785 xxx.xxx.xxx.xxx 2 7 2 1 132706 2107890 184.105.139.90 35315 xxx.xxx.xxx.xxx 5 7 2 1 350936 2206670 191.96.249.61 30296 xxx.xxx.xxx.xxx 3 7 2 1 59063 2226284 195.22.127.173 40060 xxx.xxx.xxx.xxx 2 7 2 1 20615 2253429 184.105.139.114 56609 xxx.xxx.xxx.xxx 4 7 2 1 604491 2291452 104.243.41.52 123 xxx.xxx.xxx.xxx 2 7 2 1 85831 2381504 103.9.78.129 50367 xxx.xxx.xxx.xxx 2 7 2 1 868629 2449128 167.88.15.18 40815 xxx.xxx.xxx.xxx 2 7 2 1 182471 2525650 167.88.180.82 40640 xxx.xxx.xxx.xxx 2 7 2 1 66892 2715823 192.158.229.240 39284 xxx.xxx.xxx.xxx 4 7 2 1 163873 2759391 51.15.45.102 45371 xxx.xxx.xxx.xxx 2 7 2 1 92720 2768083 185.198.58.55 18637 xxx.xxx.xxx.xxx 2 7 0 1 802096 2787683 123.249.24.197 40362 xxx.xxx.xxx.xxx 37 7 2 1 85431 2983252 167.88.180.26 49125 xxx.xxx.xxx.xxx 4 7 2 1 60114 3023906 188.213.49.83 34969 xxx.xxx.xxx.xxx 2 7 2 1 254056 3095396 45.76.24.165 41025 xxx.xxx.xxx.xxx 2 7 2 1 107397 3103557 213.183.54.46 40409 xxx.xxx.xxx.xxx 5 7 2 1 206100 3224158 145.239.237.23 35814 xxx.xxx.xxx.xxx 2 7 2 1 571497 3264230 165.227.220.24 39557 xxx.xxx.xxx.xxx 2 7 2 1 52796 3292818 123.249.35.214 47756 xxx.xxx.xxx.xxx 2 7 2 1 242695 3296347 123.249.76.52 59698 xxx.xxx.xxx.xxx 8 7 2 1 246226 3446607 123.249.79.178 52301 xxx.xxx.xxx.xxx 2 7 2 1 839605 3455884 207.254.182.131 52337 xxx.xxx.xxx.xxx 4 7 2 1 1384 3648002 185.55.218.109 37602 xxx.xxx.xxx.xxx 2 7 2 1 752428 3652434 128.14.61.111 53586 xxx.xxx.xxx.xxx 3 7 2 1 103699 3796467 104.238.146.66 52224 xxx.xxx.xxx.xxx 2 7 2 1 138668 3837468 95.215.62.72 42111 xxx.xxx.xxx.xxx 4 7 2 1 608618 3932262 45.76.195.157 59987 xxx.xxx.xxx.xxx 2 7 2 1 143642 4096101 123.249.79.232 40165 xxx.xxx.xxx.xxx 4 7 2 1 146715 4317577 86.105.9.86 55857 xxx.xxx.xxx.xxx 4 7 2 1 115972 4329305 217.147.89.197 49717 xxx.xxx.xxx.xxx 4 7 2 1 314874 4463013 182.18.22.246 58611 xxx.xxx.xxx.xxx 3 7 2 1 359548 4485937 185.82.203.107 56661 xxx.xxx.xxx.xxx 7 7 2 1 176060 4516810 79.124.60.148 58043 xxx.xxx.xxx.xxx 2 7 2 1 687406 4684505 185.107.94.66 46254 xxx.xxx.xxx.xxx 2 7 2 1 1263073 4750583 191.96.249.84 49259 xxx.xxx.xxx.xxx 2 7 2 1 329846 5160890 111.121.193.201 6065 xxx.xxx.xxx.xxx 3 7 0 1 101832 5558503 185.188.207.15 33999 xxx.xxx.xxx.xxx 3 7 2 1 90416 5655119 185.117.74.118 52973 xxx.xxx.xxx.xxx 2 7 2 1 2174 5717159 185.82.203.58 59170 xxx.xxx.xxx.xxx 2 7 2 1 47838 5847404 185.162.128.66 39141 xxx.xxx.xxx.xxx 2 7 2 1 4837 5895126All IP addresses with only 1 packet removed.
2018-01-05 Mastercard securecode of een hele goeie phishing poging 5 months ago
Ik wilde vandaag iets betalen in een website en die kwam vervolgens met "Mastercard securecode". Alleen de manier waarop was dusdanig dat ik de betaling afgebroken heb omdat ik het niet vertrouwde. De afhandeling van Mastercard securecode was binnen een iframe van de website, in een compleet andere stijl dan de website. Vervolgens bleek bij het opvragen van details dat dat iframe komt van https://www.securesuite.co.uk/ing_retail/ wat geen EV certificaat heeft. Na het vragen om de creditcard gegevens kwam een vraag over de rekening die gekoppeld is aan de creditcard en een geboortedatum. Of dat gaat om mijn geboortedatum of die van de persoon van wie de creditcard is stond er niet bij. Dus een ernstige phishing poging of een slechte implementatie van het voorkomen van fraude. Ooit heb ik de mastercard secure code ingesteld, en daar werd ook niet naar gevraagd. Ik heb er voor gekozen de betaling af te breken. In 2010 schreef al iemand hierover: Verified by Visa and Mastercard SecureCode are broken and need to be fixed. Sindsdien is de enige verandering dat ik nu een EV certificaat op zo'n site zou verwachten. En dat heeft www.securesuite.co.uk niet.
2018-01-01 Making my own web stuff more robust 5 months ago
In building the new homeserver there is also time to test things and improve robustness a bit (although I should not overdo it). The one thing that forces me to look at some web-code again is that the new servers run PHP version 7. Some of my code is giving warnings, time to fix that. But I haven't written any serious PHP in ages, I just rewrote sites in mod_perl. So my PHP is rusty and needs work, especially with PHP 7. It's a good thing I use version management, which allows me to test the fixes on the development version(s) of the site and push them to the production version when I'm happy with the results. Some of the things I notice that could improve go on the todo list. One thing I did notice and fixed right away was that the CVS metadata inside the web directories could be requested too. Although I find no serious security information in there it is still an unwanted information leak.
2017-12-26 Some extra noise in sshd attempts 5 months ago
This morning I noticed some to me new amounts of sshd noise in the log:Dec 26 01:55:43 server sshd[31415]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 01:56:24 server sshd[31466]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 01:56:53 server sshd[31475]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 01:57:33 server sshd[31499]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 01:58:17 server sshd[31691]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 01:58:51 server sshd[31749]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 01:59:32 server sshd[31773]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140Dec 26 12:07:58 server sshd[16434]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 12:08:55 server sshd[16687]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140 Dec 26 12:09:52 server sshd[16743]: Bad protocol version identification '\200F\001\003\001' from 185.110.132.140Going on and on and on and.. So I looked it up and found How to block Bad protocol version? · Issue #1284 · fail2ban/fail2ban · GitHub which has a simple rule to block this with fail2ban. As soon as the sshd.local was loaded a block was set for 185.110.132.140.
2017-12-11 Vijf jaar later een hackcontest (CTF) mee georganiseerd 6 months ago
Vijf jaar geleden deed ik mee aan de hackcontest ter ere van 20 jaar SURFcert. Vijf jaar verder ben ik zelf lid van het SURFcert team en heb ik mee georganiseerd aan de hackcontest / capture the flag op 8 december. Dit keer was het een 'capture the flag' stijl wedstrijd waarbij teams van maximaal 4 personen streden om de eer. Bij een 'capture the flag' moet je uit diverse puzzels herkenbare 'flags' (vlaggen) vinden, zeer herkenbare speciale strings in bestanden. Ik had me vooral beziggehouden met flags in bestanden in allerlei vormen zoals commentaar in een plaatje (als morse) of een flag in een bestand in een textfile in een zip file achter een jpg file geplakt. Vrijdag hebben er 4 teams gespeeld. Ze hebben de hele dag nodig gehad en een groot deel van de uitdagingen opgelost. Er was ook een team van de UU bij, die zijn zeer eervol derde geworden. Dit keer zat ik dus aan de andere kant en zat mijn creativiteit niet in het oplossen van de challenges maar in het maken er van. Wat ik gemaakt had werd gewaardeerd en sommigen lieten zich op het verkeerde been zetten waar anderen juist dwars door mijn misleiding heen keken. Het ernstigste geval 'verstoppen in het volle zicht' (hiding in plain sight) was een flag die in een titel van de standaard webpagina zat. Niet iedereen had die gezien.
2017-11-15 Lots and lots of distributed SSH scanning 7 months ago
I am noticing lots and lots of distributed SSH scanning, not doing enough attempts from one IP address to trigger fail2ban. Timing and choice of login names used suggest a strong link between the ssh attempts even when source IPs are very different. Login names also refer to websites hosted on the same address. At a given moment I started wondering if this was just me, but others reported the same and exchanging IP address lists showed a lot of matches between attacks on totally unrelated systems.
2017-11-13 The television version of "The Cuckoo's Egg" 7 months ago
I read the Dutch version of "The Cuckoo's Egg" when it came out in 1989. Later I bought the English version. Via a complete diversion I found out this weekend the book was made into a TV documentary: The KGB, the Computer and Me which has a lot less personal diversions than the book. It is played by Clifford Stoll himself and others involved in the original story. Although the CIA guys look a bit more stereotypical than they come out in the book. A very interesting part is there is a closing remark in the documentary by Markus Hess. Now I want to get a view of the movie of the other side, '23'. The funny part is that I found this documentary from following news related to amateur radio: Cliff Stoll -- K7TA -- Has THE KNACK. And a GREAT NOVA Video. Clifford Stoll does have a callsign: K7TA
2017-10-30 I am a paranoid bastard 7 months ago
I needed to look up some gpg commands and found GPG Cheat Sheet and it had what I was looking for. Looking at this page I found this gem:
Ok, so what if you're a paranoid bastard and want to encrypt some of your own files, so nobody can break into your computer and get them? Simply encrypt them using yourself as the recipient.That makes me a paranoid bastard since I use this to store passwords and other secrets.
I needed to look up some gpg commands and found
2017-10-16 Information gathering for ssh attacks 8 months ago
Someone has been looking at websites I run to think of ssh login names to try:Oct 16 16:21:53 greenblatt sshd[19367]: Invalid user weather from 223.194.227.104 Oct 16 16:22:11 greenblatt sshd[19387]: Invalid user weatherstation from 223.194.227.104 Oct 16 16:55:07 greenblatt sshd[22596]: Invalid user weerstation from 223.194.227.104All valid and published websites on this system: http://weather.idefix.net/, http://weatherstation.idefix.net/, http://weerstation.idefix.net/.
2017-09-27 Enigmail 'partial decrypt' 8 months ago
2017-08-19 Moving virtualbookcase.com to https 10 months ago
I received a notification from the google webmaster program that chrome browser would start showing security warnings on http://www.virtualbookcase.com/ due to the search box there. The simple solution: make the site correctly available via https and redirect to the https version. I found out I already started doing the first bit and therefore the conversion was easy. Now with encrypted connections: The Virtual Bookcase.
2017-07-25 If you post about "334 VXNlcm5hbWU6" be aware what you are sharing 11 months ago
Older news items for tag security ⇒I saw someone post somewhere about problems with sending mail, with the complete session log. E-mail addresses were obfuscated, but there was a part of the session not obfuscated, which had far more interesting secrets than just e-mail addresses. It looked a bit like this:250-HELP 250-AUTH LOGIN PLAIN 250-SIZE 157286400 250-8BITMIME 250 OK AUTH LOGIN 334 VXNlcm5hbWU6 dXNlcm5hbWU= 334 UGFzc3dvcmQ6 cGFzc3dvcmQ= 235 ... authentication succeeded RSET 250 OKThose "random" letters and digits look a lot like base64, so to decode them:$ echo "VXNlcm5hbWU6" | base64 -d ; echo Username: $ echo "dXNlcm5hbWU=" | base64 -d ; echo username $ echo "UGFzc3dvcmQ6" | base64 -d ; echo Password: $ echo "cGFzc3dvcmQ=" | base64 -d ; echo passwordSo the random letters and digits are actually username and password, very interesting information. Searching for VXNlcm5hbWU6 gives me examples of usernames and passwords.