CMD AUTH LOGON CHALLENGE Server
CMD_AUTH_LOGON_CHALLENGE_Server is a Login Packet sent by the server after receiving CMD_AUTH_LOGON_CHALLENGE_Client. The client reply is the CMD_AUTH_LOGON_PROOF_Client packet.
Packet Layout
Offset | Size / Endianness | Type | Name | Description |
---|---|---|---|---|
Header | ||||
0x1 | 1 / - | uint8 | opcode | 0x00 for CMD_AUTH_LOGON_CHALLENGE |
0x2 | 1 / - | uint8 | protocol_version | Exact purpose unknown. Must be 0 for all versions. |
0x3 | 1 / - | uint8 | result | The fields below are only included if this is SUCCESS (0x00). |
Body | ||||
0x4 | 32 / Little | uint8[32] | server_public_key | SRP public server ephemeral. All SRP operations are performed with little endian values. |
0x24 | 1 / - | uint8 | generator_len | SRP generator length. Should always be 1 since the generator is never greater than 255. |
0x25 | generator_len / - | uint8 | generator | SRP generator. All SRP operations are performed with little endian values. |
(0x26) | 1 / - | uint8 | large_safe_prime_len | SRP large safe prime length. All SRP operations are performed with little endian values. Client will not read more than 32 bytes. |
(0x27) | large_safe_prime_len / Little | uint8[large_safe_prime_len] | large_safe_prime | SRP large safe prime. All SRP operations are performed with little endian values. |
(0x47) | 32 / Little | uint8[32] | salt | SRP user's salt. All SRP operations are performed with little endian values. |
(0x47) | 16 / Little | uint8[16] | crc_salt | A salt to be used in CMD_AUTH_LOGON_PROOF_Client.crc_hash. Can be all zeros. |
(1.12) Additions
(1.12) added two factor authentication PIN fields which are appended to the packet.
(2.4.3.8606) Changes
Sometime around (2) the two factor fields were repurposed to the below. They are present on (2.4.3.8606) and possibly also as early as (2.0.0). These replace the (1.12) fields from above.
Name | Value | Description |
---|---|---|
NONE | 0x00 | No additional checks verification. |
PIN | 0x01 | TOTP verification entered as a PIN. |
UNKNOWN0 | 0x02 | Unknown. Referred to as "Matrix input" in Mangos source. |
AUTHENTICATOR | 0x04 | Authenticator. |
The fields added depend on which bits are set in the security_flags field.
The following fields are only present if the appropriate bit is set.
Offset | Size / Endianness | Type | Name | Description |
---|---|---|---|---|
0x00 | 4 / Little | uint32 | pin_grid_seed | Seed value for the PIN grid on the client. Only here if the two_factor_authentication field is true. |
0x04 | 16 / Little | uint8[16] | pin_salt | Salt value for the client. Only here if the two_factor_authentication field is true. |
Offset | Size / Endianness | Type | Name | Description |
---|---|---|---|---|
0x00 | 1 / - | uint8 | unknown0 | Unknown. Statically set to 0 in Mangos. |
0x01 | 1 / - | uint8 | unknown1 | Unknown. Statically set to 0 in Mangos. |
0x02 | 1 / - | uint8 | unknown2 | Unknown. Statically set to 0 in Mangos. |
0x03 | 1 / - | uint8 | unknown3 | Unknown. Statically set to 0 in Mangos. |
0x04 | 8 / - | uint64 | unknown4 | Unknown. Statically set to 0 in Mangos. |
Offset | Size / Endianness | Type | Name | Description |
---|---|---|---|---|
0x00 | 1 / - | uint8 | unknown0 | Statically set to 1 in Mangos. |
Size
For all versions, if the result is not SUCCESS (0x00) the packet is 3 bytes.
If the result is SUCCESS (0x00):
Example Packet
Below is complete packet sent from a (1.12.1.5875) client. The values are explained as comments. This can be used for verifying packet parser implementations.
The first packet does not include the extra two factor fields.
char bytes[] = { 0x00, // Opcode: CMD_AUTH_LOGON_CHALLENGE 0x00, // Protocol Version: 0 0x00, // Result: SUCCESS (0) 0x49, 0xd8, 0xc2, 0xbc, 0x68, 0x5c, 0x2b, 0xce, 0x4a, 0xf4, 0xfa, 0x07, 0x0a, 0x47, 0x93, 0x78, 0x58, 0x78, 0x46, 0xb5, 0x83, 0xd4, 0x41, 0x82, 0x9e, 0x24, 0xd8, 0x87, 0xce, 0xda, 0x34, 0x46, // Server Public Key 0x01, // Generator Length: 1 0x07, // Generator: 7 0x20, // Large Safe Prime Length: 32 0xb7, 0x9b, 0x3e, 0x2a, 0x87, 0x82, 0x3c, 0xab, 0x8f, 0x5e, 0xbf, 0xbf, 0x8e, 0xb1, 0x01, 0x08, 0x53, 0x50, 0x06, 0x29, 0x8b, 0x5b, 0xad, 0xbd, 0x5b, 0x53, 0xe1, 0x89, 0x5e, 0x64, 0x4b, 0x89, 0xc7, 0x09, 0x87, // Large Safe Prime 0x7d, 0x8c, 0x65, 0x52, 0x66, 0xa5, 0x7d, 0xb8, 0x65, 0x3d, 0x6e, 0xa6, 0x2b, 0xb5, 0x54, 0xf2, 0x0b, 0xcf, 0x74, 0xd6, 0x4a, 0x77, 0xa7, 0xd3, 0x3d, 0xf3, 0x30, 0x90, 0x87, 0xba, 0xa3, 0x1e, // Salt 0x99, 0xa0, 0x0b, 0x21, 0x57, 0xfc, 0x37, 0x3f, 0xb3, 0x69, 0xcd, 0xd2, 0xf1, // CRC Salt 0x00, // Two factor fields enabled: False }
The second one does.
char bytes[] = { 0x00, // Opcode: CMD_AUTH_LOGON_CHALLENGE 0x00, // Protocol Version: 0 0x00, // Result: SUCCESS (0) 0x49, 0xd8, 0xc2, 0xbc, 0x68, 0x5c, 0x2b, 0xce, 0x4a, 0xf4, 0xfa, 0x07, 0x0a, 0x47, 0x93, 0x78, 0x58, 0x78, 0x46, 0xb5, 0x83, 0xd4, 0x41, 0x82, 0x9e, 0x24, 0xd8, 0x87, 0xce, 0xda, 0x34, 0x46, // Server Public Key 0x01, // Generator Length: 1 0x07, // Generator: 7 0x20, // Large Safe Prime Length: 32 0xb7, 0x9b, 0x3e, 0x2a, 0x87, 0x82, 0x3c, 0xab, 0x8f, 0x5e, 0xbf, 0xbf, 0x8e, 0xb1, 0x01, 0x08, 0x53, 0x50, 0x06, 0x29, 0x8b, 0x5b, 0xad, 0xbd, 0x5b, 0x53, 0xe1, 0x89, 0x5e, 0x64, 0x4b, 0x89, 0xc7, 0x09, 0x87, // Large Safe Prime 0x7d, 0x8c, 0x65, 0x52, 0x66, 0xa5, 0x7d, 0xb8, 0x65, 0x3d, 0x6e, 0xa6, 0x2b, 0xb5, 0x54, 0xf2, 0x0b, 0xcf, 0x74, 0xd6, 0x4a, 0x77, 0xa7, 0xd3, 0x3d, 0xf3, 0x30, 0x90, 0x87, 0xba, 0xa3, 0x1e, // Salt 0x99, 0xa0, 0x0b, 0x21, 0x57, 0xfc, 0x37, 0x3f, 0xb3, 0x69, 0xcd, 0xd2, 0xf1, // CRC Salt 0x01, // Two factor fields enabled: True 0xEF, 0xBE, 0xAD, 0xDE, // PIN grid seed: 0xDEADBEEF 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, // PIN salt }