2211ee0037
CVE description : The recv_msg_userauth_request function in svr-auth.c in Dropbear through 2018.76 is prone to a user enumeration vulnerability because username validity affects how fields in SSH_MSG_USERAUTH messages are handled, a similar issue to CVE-2018-15473 in an unrelated codebase. Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>
87 lines
2.6 KiB
Diff
87 lines
2.6 KiB
Diff
--- a/svr-authpubkey.c
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+++ b/svr-authpubkey.c
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@@ -229,14 +229,20 @@ static int checkpubkey(char* algo, unsig
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goto out;
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}
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- /* we don't need to check pw and pw_dir for validity, since
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- * its been done in checkpubkeyperms. */
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- len = strlen(ses.authstate.pw_dir);
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- /* allocate max required pathname storage,
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- * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
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- filename = m_malloc(len + 22);
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- snprintf(filename, len + 22, "%s/.ssh/authorized_keys",
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- ses.authstate.pw_dir);
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+ if (ses.authstate.pw_uid != 0) {
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+ /* we don't need to check pw and pw_dir for validity, since
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+ * its been done in checkpubkeyperms. */
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+ len = strlen(ses.authstate.pw_dir);
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+ /* allocate max required pathname storage,
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+ * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
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+ filename = m_malloc(len + 22);
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+ snprintf(filename, len + 22, "%s/.ssh/authorized_keys",
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+ ses.authstate.pw_dir);
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+ } else {
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+ filename = m_malloc(30);
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+ strncpy(filename, "/etc/dropbear/authorized_keys", 30);
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+ }
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+
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/* open the file as the authenticating user. */
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origuid = getuid();
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@@ -405,26 +411,35 @@ static int checkpubkeyperms() {
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goto out;
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}
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- /* allocate max required pathname storage,
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- * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
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- filename = m_malloc(len + 22);
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- strncpy(filename, ses.authstate.pw_dir, len+1);
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-
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- /* check ~ */
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- if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
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- goto out;
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- }
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-
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- /* check ~/.ssh */
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- strncat(filename, "/.ssh", 5); /* strlen("/.ssh") == 5 */
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- if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
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- goto out;
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- }
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-
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- /* now check ~/.ssh/authorized_keys */
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- strncat(filename, "/authorized_keys", 16);
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- if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
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- goto out;
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+ if (ses.authstate.pw_uid == 0) {
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+ if (checkfileperm("/etc/dropbear") != DROPBEAR_SUCCESS) {
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+ goto out;
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+ }
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+ if (checkfileperm("/etc/dropbear/authorized_keys") != DROPBEAR_SUCCESS) {
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+ goto out;
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+ }
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+ } else {
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+ /* allocate max required pathname storage,
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+ * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
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+ filename = m_malloc(len + 22);
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+ strncpy(filename, ses.authstate.pw_dir, len+1);
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+
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+ /* check ~ */
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+ if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
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+ goto out;
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+ }
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+
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+ /* check ~/.ssh */
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+ strncat(filename, "/.ssh", 5); /* strlen("/.ssh") == 5 */
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+ if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
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+ goto out;
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+ }
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+
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+ /* now check ~/.ssh/authorized_keys */
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+ strncat(filename, "/authorized_keys", 16);
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+ if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
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+ goto out;
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+ }
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}
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/* file looks ok, return success */
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