diff options
Diffstat (limited to 'libcli/auth/credentials.c')
| -rw-r--r-- | libcli/auth/credentials.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/libcli/auth/credentials.c b/libcli/auth/credentials.c index b6c8ba281ba..e2bc82809b7 100644 --- a/libcli/auth/credentials.c +++ b/libcli/auth/credentials.c @@ -25,10 +25,40 @@ #include "../lib/crypto/crypto.h" #include "libcli/auth/libcli_auth.h" #include "../libcli/security/dom_sid.h" +#include "lib/util/util_str_escape.h" + + +bool netlogon_creds_is_random_challenge(const struct netr_Credential *challenge) +{ + /* + * If none of the first 5 bytes of the client challenge is unique, the + * server MUST fail session-key negotiation without further processing + * of the following steps. + */ + + if (challenge->data[1] == challenge->data[0] && + challenge->data[2] == challenge->data[0] && + challenge->data[3] == challenge->data[0] && + challenge->data[4] == challenge->data[0]) + { + return false; + } + + return true; +} + +void netlogon_creds_random_challenge(struct netr_Credential *challenge) +{ + ZERO_STRUCTP(challenge); + while (!netlogon_creds_is_random_challenge(challenge)) { + generate_random_buffer(challenge->data, sizeof(challenge->data)); + } +} static void netlogon_creds_step_crypt(struct netlogon_creds_CredentialState *creds, const struct netr_Credential *in, struct netr_Credential *out) + { if (creds->negotiate_flags & NETLOGON_NEG_SUPPORTS_AES) { AES_KEY key; @@ -422,6 +452,7 @@ struct netlogon_creds_CredentialState *netlogon_creds_server_init(TALLOC_CTX *me { struct netlogon_creds_CredentialState *creds = talloc_zero(mem_ctx, struct netlogon_creds_CredentialState); + bool ok; if (!creds) { return NULL; @@ -434,6 +465,20 @@ struct netlogon_creds_CredentialState *netlogon_creds_server_init(TALLOC_CTX *me dump_data_pw("Server chall", server_challenge->data, sizeof(server_challenge->data)); dump_data_pw("Machine Pass", machine_password->hash, sizeof(machine_password->hash)); + ok = netlogon_creds_is_random_challenge(client_challenge); + if (!ok) { + DBG_WARNING("CVE-2020-1472(ZeroLogon): " + "non-random client challenge rejected for " + "client_account[%s] client_computer_name[%s]\n", + log_escape(mem_ctx, client_account), + log_escape(mem_ctx, client_computer_name)); + dump_data(DBGLVL_WARNING, + client_challenge->data, + sizeof(client_challenge->data)); + talloc_free(creds); + return NULL; + } + creds->computer_name = talloc_strdup(creds, client_computer_name); if (!creds->computer_name) { talloc_free(creds); |