From 8dbbed10870378f1b2c3cf3df2ea7edca7617096 Mon Sep 17 00:00:00 2001 From: Sergio Correia Date: Wed, 14 Jun 2023 10:53:20 -0300 Subject: [PATCH] Fix race condition when creating/rotating keys (#123) When we create/rotate keys using either the tangd-keygen and tangd-rotate-keys helpers, there is a small window between the keys being created and then the proper ownership permissions being set. This also happens when there are no keys and tang creates a pair of keys itself. In certain situations, such as the keys directory having wide open permissions, a user with local access could exploit this race condition and read the keys before they are set to more restrictive permissions. To prevent this issue, we now set the default umask to 0337 before creating the files, so that they are already created with restrictive permissions; afterwards, we set the proper ownership as usual. Issue reported by Brian McDermott of CENSUS labs. Fixes CVE-2023-1672 Refer: https://github.com/latchset/tang/commit/8dbbed10870378f1b2c3cf3df2ea7edca7617096 https://ubuntu.com/security/CVE-2023-1672 Reviewed-by: Sergio Arroutbi Signed-off-by: Sergio Correia --- src/tangd-keygen | 3 +++ 1 file changed, 3 insertions(+) diff --git a/src/tangd-keygen b/src/tangd-keygen index 20d498e..d894ece 100755 --- a/src/tangd-keygen +++ b/src/tangd-keygen @@ -27,6 +27,9 @@ fi [ $# -eq 3 ] && sig=$2 && exc=$3 +# Set default umask for file creation. +umask 0337 + jwe=`jose jwk gen -i '{"alg":"ES512"}'` [ -z "$sig" ] && sig=`echo "$jwe" | jose jwk thp -i-` echo "$jwe" > $1/$sig.jwk -- 2.33.0