From 8f1046a25f44812a48a0d05b0a364c5134cf0589 Mon Sep 17 00:00:00 2001 From: Tomas Mraz Date: Tue, 11 Mar 2014 10:16:58 +0100 Subject: [PATCH] fix CVE-2013-7041: use case sensitive comparison in pam_userdb --- pam-1.1.8-cve-2013-7041.patch | 52 +++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 pam-1.1.8-cve-2013-7041.patch diff --git a/pam-1.1.8-cve-2013-7041.patch b/pam-1.1.8-cve-2013-7041.patch new file mode 100644 index 0000000..96fa916 --- /dev/null +++ b/pam-1.1.8-cve-2013-7041.patch @@ -0,0 +1,52 @@ +From 57a1e2b274d0a6376d92ada9926e5c5741e7da20 Mon Sep 17 00:00:00 2001 +From: "Dmitry V. Levin" +Date: Fri, 24 Jan 2014 22:18:32 +0000 +Subject: [PATCH] pam_userdb: fix password hash comparison + +Starting with commit Linux-PAM-0-77-28-g0b3e583 that introduced hashed +passwords support in pam_userdb, hashes are compared case-insensitively. +This bug leads to accepting hashes for completely different passwords in +addition to those that should be accepted. + +Additionally, commit Linux-PAM-1_1_6-13-ge2a8187 that added support for +modern password hashes with different lengths and settings, did not +update the hash comparison accordingly, which leads to accepting +computed hashes longer than stored hashes when the latter is a prefix +of the former. + +* modules/pam_userdb/pam_userdb.c (user_lookup): Reject the computed +hash whose length differs from the stored hash length. +Compare computed and stored hashes case-sensitively. +Fixes CVE-2013-7041. + +Bug-Debian: http://bugs.debian.org/731368 +--- + modules/pam_userdb/pam_userdb.c | 9 ++++++--- + 1 file changed, 6 insertions(+), 3 deletions(-) + +diff --git a/modules/pam_userdb/pam_userdb.c b/modules/pam_userdb/pam_userdb.c +index de8b5b1..ff040e6 100644 +--- a/modules/pam_userdb/pam_userdb.c ++++ b/modules/pam_userdb/pam_userdb.c +@@ -222,12 +222,15 @@ user_lookup (pam_handle_t *pamh, const char *database, const char *cryptmode, + } else { + cryptpw = crypt (pass, data.dptr); + +- if (cryptpw) { +- compare = strncasecmp (data.dptr, cryptpw, data.dsize); ++ if (cryptpw && strlen(cryptpw) == (size_t)data.dsize) { ++ compare = memcmp(data.dptr, cryptpw, data.dsize); + } else { + compare = -2; + if (ctrl & PAM_DEBUG_ARG) { +- pam_syslog(pamh, LOG_INFO, "crypt() returned NULL"); ++ if (cryptpw) ++ pam_syslog(pamh, LOG_INFO, "lengths of computed and stored hashes differ"); ++ else ++ pam_syslog(pamh, LOG_INFO, "crypt() returned NULL"); + } + }; + +-- +1.8.3.1 +