CVE-2016-6210: Mitigate user enumeration via covert timing channel.

1 files changed, 60 insertions, 0 deletions

diff --git a/debian/patches/CVE-2016-6210-3.patch b/debian/patches/CVE-2016-6210-3.patch
new file mode 100644
index 000000000..303c34ee1
--- /dev/null
+++ b/debian/patches/CVE-2016-6210-3.patch
@@ -0,0 +1,60 @@
+From abde8dda29c2db2405d6fbca2fe022430e2c1177 Mon Sep 17 00:00:00 2001
+From: Darren Tucker <dtucker@zip.com.au>
+Date: Thu, 21 Jul 2016 14:17:31 +1000
+Subject: Search users for one with a valid salt.
+
+If the root account is locked (eg password "!!" or "*LK*") keep looking
+until we find a user with a valid salt to use for crypting passwords of
+invalid users.  ok djm@
+
+Origin: upstream, https://anongit.mindrot.org/openssh.git/commit/?id=dbf788b4d9d9490a5fff08a7b09888272bb10fcc
+Bug-Debian: https://bugs.debian.org/831902
+Last-Update: 2016-07-22
+
+Patch-Name: CVE-2016-6210-3.patch
+---
+ openbsd-compat/xcrypt.c | 24 +++++++++++++++---------
+ 1 file changed, 15 insertions(+), 9 deletions(-)
+
+diff --git a/openbsd-compat/xcrypt.c b/openbsd-compat/xcrypt.c
+index 8913bb8..cf6a9b9 100644
+--- a/openbsd-compat/xcrypt.c
++++ b/openbsd-compat/xcrypt.c
+@@ -65,7 +65,9 @@
+ 
+ /*
+  * Pick an appropriate password encryption type and salt for the running
+- * system.
++ * system by searching through accounts until we find one that has a valid
++ * salt.  Usually this will be root unless the root account is locked out.
++ * If we don't find one we return a traditional DES-based salt.
+  */
+ static const char *
+ pick_salt(void)
+@@ -78,14 +80,18 @@ pick_salt(void)
+        if (salt[0] != '\0')
+                return salt;
+        strlcpy(salt, "xx", sizeof(salt));
+-       if ((pw = getpwuid(0)) == NULL)
+-               return salt;
+-       passwd = shadow_pw(pw);
+-       if (passwd[0] != '$' || (p = strrchr(passwd + 1, '$')) == NULL)
+-               return salt;  /* no $, DES */
+-       typelen = p - passwd + 1;
+-       strlcpy(salt, passwd, MIN(typelen, sizeof(salt)));
+-       explicit_bzero(passwd, strlen(passwd));
++       setpwent();
++       while ((pw = getpwent()) != NULL) {
++               passwd = shadow_pw(pw);
++               if (passwd[0] == '$' && (p = strrchr(passwd+1, '$')) != NULL) {
++                       typelen = p - passwd + 1;
++                       strlcpy(salt, passwd, MIN(typelen, sizeof(salt)));
++                       explicit_bzero(passwd, strlen(passwd));
++                       goto out;
++               }
++       }
++ out:
++       endpwent();
+        return salt;
+ }
+