"Copy as curl" from browser, we can save an image from a Twitter DM.

twitter-dm-image-curl.txt

% curl 'https://ton.twitter.com/i/ton/data/dm/1600870219324465156/1600870190459256832/KM0EBzij.jpg:small' \
-X 'GET' \
-H 'Cookie: _ga=GA1.2.1578974351.1658522778; _gid=GA1.2.1415303809.1669565137; twid=u%3D1600710747004305409; att=1-EAfZonmiIFAabN7WJFAYruyozkoR4R1UXTi9Mrbd; auth_token=0f57cc642e5efc86e77113c4c6e26e63f4a8277c; ct0=6affe5131db8f27b7e737d10cc4db10ba7a18e09c64ae1049daf2113619feb98bb3fc2d2c2a9dc0bbb4890329e2871639a67cdd121c5962552fdae23dc2238c776da3a6296484e3b51ee9da53abb120a; kdt=1pjaQNrUHWOACrgtiPbMODtq9EtyfO2zjyqIRn2M; _twitter_sess=BAh7CSIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNo%250ASGFzaHsABjoKQHVzZWR7ADoPY3JlYXRlZF9hdGwrCOIYHPCEAToMY3NyZl9p%250AZCIlNWZjNjY2YTUwMjIwYjY2ODU0OGMzNDFlNjdmYzg2NmU6B2lkIiVkZTg1%250ANjg4ZjJkMDZjZGM1MDlhNjIyMjJlMDQ5ZTA2NQ%253D%253D--5208257722568ae7fb82098c4a047426afb617b2; external_referer=5R4llnU6LiS6nKIFlrLdVgSXOiDO0qILODRlwl3mUPKfPbBdozq%2F%2BhlJutu4u37W|1|8e8t2xd8A2w%3D; dnt=1; guest_id=v1%3A167047567821699925; personalization_id="v1_jeT69pPEhhQw02CPfmk+gA=="; guest_id_ads=v1%3A157695208658630181; guest_id_marketing=v1%3A157695208658630181; remember_checked_on=1' \
-H 'Accept: image/webp,image/png,image/svg+xml,image/*;q=0.8,video/*;q=0.8,*/*;q=0.5' \
-H 'Accept-Encoding: gzip, deflate, br' \
-H 'Host: ton.twitter.com' \
-H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.3 Safari/605.1.15' \
-H 'Accept-Language: en-us' \
-H 'Referer: https://twitter.com/' \
-H 'Connection: keep-alive' > wk-bk.jpeg
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 22425  100 22425    0     0   109k      0 --:--:-- --:--:-- --:--:--  109k
% open wk-bk.jpeg