Re:Perl code that is syntactically correct only on Fridays
by lloeki on Wednesday February 16, 2022 @09:57AM
(#30360759)
Bash even reads the file as it goes, so if you run a "long-running" script (a sleep is enough), edit far enough down, and write the file again, the previously started bash will end up running the new content once it gets up to reading where the change happened.
[ Parent
| on HN ]
Re:Perl code that is syntactically correct only on Fridays
by saba2008 on Wednesday February 16, 2022 @11:15AM
(#30361882)
You can exploit it do distinguish whenever script is `curl | bash`'ed.
Add `sleep 1`, and detect pause on server. Then, if pause detected - serve attack payload. If not - somebody is careful enough to download and audit, so serve just the script.
Re:Perl code that is syntactically correct only on Fridays
by jwilk on Wednesday February 16, 2022 @11:45AM
(#30362242)
https://www.idontplaydarts.com/2016/04/detecting-curl-pipe-b...
Discussed on HN:
2020: https://news.ycombinator.com/item?id=25356757 (133 comments)
2018: https://news.ycombinator.com/item?id=17636032 (146 comments)
2016: https://news.ycombinator.com/item?id=11532599 (122 comments)