. o O o . I N S I D E N D S . o O o . by Simple Nomad . o O o . [ Abstract ] . o O o . This document will present a technical view of the layout of Novell's Netware Directory Services (NDS). The emphasis here is mainly from a security perspective, and tries to point out several areas of weakness that need to be reinforced. Novell has touted the advanced security features built into NDS as being superior to other network operating systems, including statements that passwords cannot be recovered, even by administrators. This document will examine how to recover the passwords, and give a complete layout of NDS. . o O o . [ Audience ] . o O o . While I am probably more well known for the Netware Hack FAQ and presentation of security issues related to Netware from an intruder perspective, this document is geared more toward those simply interested in how things work. But due to the fact that I am covering security issues, the inference is still there. I do assume some basic Netware knowledge, and I make use of some examples of C code to explain some concepts, therefore knowledge of C coding might be of some help. I have tried to make this as non-technical as possible, but due to the material being covered, unless you are a bit head this is probably going to be a very dry read. . o O o . [ Credits ] . o O o . If you read nothing, or just a paragraph or two, please at least read these credits. I did have some support during this project, and I want to acknowledge a few people. For some background help and some code snippets, itsme provided a lot. Also I bounced ideas off of Greg Miller, Al Grant, and Rx2. Thanks a lot. Lab assistance was provided by Mr. Wizard and Fourth Stooge. Mr. Wizard provided several examples of BACKUP.DS so I had multiple copies to play with, and Fourth Stooge provided hardware in the form of hard drives for the lab. Without the drive space I would have been very limited, and without the extra BACKUP.DS files I would not have been able to accurately cross check the different 4.x Netware versions for consistancy. Finally I would like to thank two more people, my wife for naming the project Pandora after hearing my explanation of what the hell I was doing in the lab for hours at a time, and Marcus Williamson for trying to keep me honest through a series of email exchanges where he constantly tried to get me to admit that this was NOT a security breach (that is left for you, the humble reader, to decide). . o O o . [ Tools ] . o O o . There were a number of tools used in the preparation of this document. The two main tools were a hex dump utility and a hex calculator. By examining the NDS files in the hex dump utility and playing with some of the values, a picture of how the files were tied together emerged. I also used a C compiler and wrote several utilities to extract and examine the data. Most of the utilities were short programs of little use to the general public, but as I continued to explore I wrote more useful utilities for NDS extraction. These utilities, along with a copy of this document were released as a set called Pandora. Pandora is available from http://www.nmrc.org/files/netware, or from a link on the Pandora Home Page at http://www.nmrc.org/pandora. . o O o . [ Background ] . o O o . NDS is a distributed database for Netware 4.x that provides access to all network resources. It allows a user to use a single login to a Netware environment and approach a group of Netware servers as a single entity. GUI interfaces provide easy management for administrators. NDS itself consists of 4 core files. These files include PARTITIO.NDS, ENTRY.NDS, VALUE.NDS, and BLOCK.NDS. The files are stored on the SYS: volume in a hidden directory called _NETWARE. This directory cannot be directly accessed from a user login session, including an administrator. All objects addressed by the server are located within the ENTRY.NDS file. All named attributes have a record, and all administrator-created items have a record. For example, there is a record called USER which contains information about the USER property itself, and a record for a user called Admin which contains information about that particular USER object. Values associated with ENTRY records are stored in one and sometimes two files. VALUE.NDS will contain up to 16 bytes of data about an ENTRY record. Why so little? Well, 16 bytes is EXACTLY what is needed for one ACL entry. ACL entries are the most common VALUE records. If more than 16 bytes of information is needed, the VALUE record has a pointer to BLOCK.NDS. This file's records can contain up to 120 bytes of data. If still more room is needed, extra BLOCK records can be linked together via pointers. The partition information is contained within PARTITIO.NDS, which is basically used to keep track of a minimal amount of information that helps NDS replicate and sync up the data between servers. . o O o . [ Accessing NDS ] . o O o . First off, to explore NDS one must retrieve a copy from a server. This is actually easier than it seems. The two main ways to get copies of NDS involve console access, and will interrupt server access during retrieval. If you are pulling a copy of NDS off of a server, make sure you wait until a time when user activity is at a minimal. The interruption will mean that access to network resources that have not been authenticated will not work. If users are already logged in, they should not notice any interruptions. This is similiar to the impact encountered during a DSREPAIR. The first method involves using either RCONSOLE or direct console access and loading an NLM that allows access to SYS:_NETWARE to retrieve the copies. Two such NLMs are JCMD.NLM and NETBASIC.NLM. JCMD.NLM is freeware available on the Internet, but NETBASIC.NLM is the prefered method, as this NLM is bundled with Netware 4.11. Loading NETBASIC and typing "shell" drops you to a pseudo DOS-like environment. From here you can simply cd into SYS:_NETWARE, and copy the *.NDS files to another location on the server (for example SYS:LOGIN). Remember, DS.NLM must be unloaded to do this. For the faint of heart, there is one other method using DSMAINT.NLM, or NDSCOPY.NLM that came with an older version of DSMAINT.NLM. These are available from Novell's web site. The by-product of running these NLMs is a file called BACKUP.DS that is placed in the SYS:SYSTEM directory. This is my prefered method of retrieval, and you get all of the NDS files in one package. It should be obvious, but if your server console is compromised, an intruder could do this as well. And if the file system is compromised, BACKUP.DS will be a tempting target. So keep BACKUP.DS in a safe place if you wish to protect NDS, and if no longer needed, delete it. . o O o . [ NDS File Structure ] . o O o . The 4 files -- ENTRY.NDS, VALUE.NDS, BLOCK.NDS, and PARTITIO.NDS -- are binary files that consist of individual records. Here is the structure (as well as I can determine without the source code) for each record. Included are my comments: typedef unsigned long uint32; typedef unsigned int uint16; typedef unsigned char uint8; /* * struct for ENTRY.NDS records */ typedef struct entry { uint32 selfOffset; /* Offset in ENTRY.NDS. If this is the first record, it is 0x00000000 followed by 0x0000014e for the second record, etc. */ uint32 checkSum; /* I assume a checksum */ uint32 val1; /* Unsure, 0xfeffffff. */ uint32 val2; /* Unsure, 0xffffffff. */ uint32 peer; /* Offset to a peer record. */ uint32 firstChild; /* Offset to first child record. If no kids, 0xffffffff. */ uint32 lastChild; /* Offset to second child record. If no kids, 0xffffffff. */ uint32 firstValue; /* Offset in VALUE.NDS of first attribute. They are usually kept in order in VALUE.NDS, but since they are crossed referenced in VALUE.NDS they don't have to be.*/ uint32 id; /* The Object ID of the record. */ uint32 partitionID; /* The partition ID of the record. */ uint32 parentID; /* The parent's Object ID, if no parent it is 0xffffffff. */ uint32 val3; /* No idea. Usually a small number.*/ uint32 val4; /* No idea. 0x00000000. */ uint32 subordinates; /* Number of subordinates. This can include other objects besides children. */ uint32 classID; /* The "type" of Object ID. */ uint32 creatTime1, /* When object was created. */ creatTime2; uint32 modTime1, /* When object was last modified. */ modTime2; uint8 name[258]; /* Dreaded unicode describing the record. If a user object it will be the common name. */ } ENTRY; /* size=334 */ /* * struct for VALUE.NDS records */ typedef struct value { uint32 selfOffset; /* Offset in VALUE.NDS. If this is the first record, it is 0x00000000 followed by 0x00000040 for the second record, etc. */ uint32 checkSum; /* I assume a checksum */ uint32 val1; /* Unsure, usually 0xfeffffff. */ uint32 val2; /* Unsure, usually 0xffffffff. */ uint32 nextVal; /* The next Value record's offset. */ uint32 firstBlock; /* Offset in BLOCK.NDS if used. */ uint32 entryID; /* Type of record in ENTRY.NDS. */ uint32 typeID; /* Type of VALUE record. */ uint32 val3; /* No idea. Usually a small number.*/ uint32 creatTime1, /* When object was created(?), */ creatTime2; /* and modified(?). */ uint32 length; /* Length of data. */ uint8 data[16]; /* Start of data, unless there is a small amount of data, then it's all here. */ } VALUE; /* size=64 */ /* * struct for BLOCK.NDS records */ typedef struct block { uint32 selfOffset; /* Offset in BLOCK.NDS. If this is the first record, it is 0x00000000 followed by 0x00000080 for the second record, etc. */ uint32 checkSum; /* I assume a checksum */ uint32 val1; /* Unsure. */ uint32 nextBlock; /* Next record if data>120. */ uint32 valueOffset; /* Offset in VALUE.NDS (backlink) */ uint8 data[120]; } BLOCK; /* size=128 */ /* * struct for PARTITIO.NDS records */ typedef struct partition { uint32 selfOffset; /* Offset in PARTITIO.NDS. If this is the first record, it is 0x00000000 followed by 0x00000028 for the second record, etc. */ uint32 checkSum; /* I assume a checksum */ uint32 val1; /* Unsure. */ uint32 id; /* ID of record. */ uint32 entryID; /* ID in ENTRY.NDS */ uint32 replicaID; /* Replica ID (??) in ENTRY.NDS */ uint32 val2; /* Unsure. */ uint32 val3; /* Unsure. */ uint32 timeStamp1, /* Probably used to keep things in sync */ timeStamp2; } PARTITIO; /* size=40 */ As you can see I've had to guess at a lot of these, but I think there is enough there to allow you to see what is in NDS. By comparing the BACKUP.DS and *.NDS files, along with the selfOffset at the beginning of each record, a picture begins to emerge. As we push through this document, you will need to refer back to these structures. . o O o . [ BACKUP.DS Structure ] . o O o . If you retrieve BACKUP.DS, you need to reconstruct the NDS files into their original 4 components. The structure of BACKUP.DS is as follows - |---------------| | HEADER | <------- Header. |---------------| | Offset to end | <------- This offset is located just past the header. | of ENTRY.NDS | (unsigned long int)n = Offset/sizeof(VALUE) |---------------| gets the number of records. | ENTRY.NDS | |---------------| | Offset to end | <------- (unsigned long int)n = Offset/sizeof(VALUE) | of VALUE.NDS | gets the number of records. |---------------| | VALUE.NDS | |---------------| | Offset to end | <------- (unsigned long int)n = Offset/sizeof(BLOCK) | of BLOCK.NDS | gets the number of records. |---------------| | BLOCK.NDS | |---------------| | Offset to end | <------- (unsigned long int)n = Offset/sizeof(PARTITIO) |of PARTITIO.NDS| gets the number of records. |---------------| | PARTITIO.NDS | |---------------| The BACKUP.DS header section has a rather odd structure consisting of variable data. While I have taken a look at it, it is not that important when searching for NDS files. It does contain the server and tree name, and in multi-server environments you will get a copy of the SAP table, or at least something with a lot of the same information. This is there, I assume, so that if and/or when you recover NDS your server will have a fairly clear view of what the network last looked like.

From this information you should be able to write a program in C that will take a BACKUP.DS file and make the 4 NDS files. If you do not know how (or do not have the time) to write such a program, use CONVERT.EXE from Pandora to recreate NDS files from BACKUP.DS. . o O o . [ Fun and Games ] . o O o . It is possible, starting with PARTITIO.NDS and its reference to ENTRY.NDS, to follow each cross reference and get a complete dump of NDS. I have not written such a utility, nor would I care to. But one of the things that interested me the first time I looked at BACKUP.DS in a hex viewer was that I could possibly get user passwords. Novell has said that this was impossible, and that Netware 4.x uses a public key encryption scheme for authentication. However this did not stop me from exploring and learning about the size and structure of individual pieces and attributes. The details of WHAT can be found are much more interesting than how I discovered the location of the private key. So what follows is the process to get a private key. The logical thing is to determine what ENTRY.classID value represents a user object. This is fairly easy to determine by examining ENTRY records until a user record is found (CN=Admin makes it easy to find). However this may not be consistent between servers. Although I found that the classID for users is usually 0x010000af, in one case I found this value to be different. So to ensure that you have found the correct classID, search all of ENTRY.NDS looking for objects with the name of "User". If there are two, the last one is the correct one. This particular object's classID is the ID that says an ENTRY.NDS record is a user record. All objects are stored this way in NDS, so the next thing to do is determine the classID associated with the Private Key object. This can be done by searching for "Priv". Typically this is 0x01000045, although in one case I found it was not. Therefore it is important to check to make sure. To simplify searching of NDS records, all "system" related objects, such as the User object and Private Key object, all have classIDs of 0xffffffff. To quicken the search, simply look for ENTRY.NDS records with a classID of 0xffffffff and a name of "User" or "Priv" and you will have the object ID at ENTRY.id needed for later searching. Let's say that we have searched ENTRY.NDS and retrieved 0x010000af for User objects and 0x01000045 for Private Key objects. To retrieve user and password info from NDS, we first need to search ENTRY.NDS for records with a classID of 0x010000af. This will get us all of the user records, and by dumping ENTRY.name you will have the Common Name (CN) of each user. Getting the ENTRY.id will help us in the next step. Searching each VALUE.NDS record for the ENTRY.id in VALUE.entryID and 0x01000045 in VALUE.typeID will get us the start of the Private Key. The private key's size=324, so you will have to follow the VALUE.firstBlock offset in BLOCK.NDS to retrieve all of the data. Here is an example of the first several bytes of a private key: User "Simple" (object ID=090000c3) private key: c3 00 00 09 08 00 00 00 8d 49 e4 55 f2 5a 57 0e bb 8a f9 f6 ea 3a f6 88 01 00 00 00 01 00 60 00 20 01 19 01 38 74 08 89 02 c4 97 a3 43 5d 00 86 etc... Comparing this private key to other private keys, a pattern begins to emerge from them. The private key has the following structure: typedef struct PRIV_KEY { uint32 objectID; /* Object ID of user. */ uint16 pwLength; /* Password length. */ uint16 var1; /* Unsure. Perhaps unused. */ uint8 pw[16]; /* The password, one way hashed. */ uint32 var2; /* No idea, is always 0x00000001 */ uint16 var3; /* No idea, is always 0x0001 */ uint16 var4; /* No idea, is always 0x0006 */ uint32 var5; /* No idea, is always 0x01190120 */ uint8 key[288]; /* The private key, encrypted. */ uint32 var6; /* No idea... */ uint32 var7; /* No idea... */ uint32 var8; /* No idea... */ uint32 var9; /* No idea... */ } PRIV_KEY; /* size=340 */ While it is interesting that on occassion you will see var8 and var9 equal the first four characters of the user's common name in unicode, the thing that really looks interesting is the one way encrypted hash. From studying bindery files it is known that the Netware 3.x password is this exact same length. By using the Netware 3.x algorithm that has been floating around on the Internet for a couple of years it turns out that YES this is the one way hash. Retrieving this info from ENTRY.NDS, VALUE.NDS, and BLOCK.NDS to specifically grab info for password cracking could be done by simply looking for the various IDs at the various offsets and writing them out to a file. To simplify this process, you could use EXTRACT.EXE from Pandora. EXTRACT.EXE creates an NDS-style password file. . o O o . [ Security Implications ] . o O o . If you now have the user's common name, the object ID, the one way hash, and the algorithm, it should simply be a matter of time to crack the password. The algorithm used by Novell requires the length of the password, the password itself, and the object ID to generate the one way hash. Therefore a dictionary attack could be quite fruitful. A hard-to-guess password will slow down the process of cracking the password considerably. However, the algorithm converts the password to upper case before encryption, and we know the password length before we even start cracking. While brute force attacks can be lengthy and tiresome, such an attack is not entirely out of the question. To demonstrate this, you can use CRYPTO.EXE and CRYPTO2.EXE from Pandora to perform brute force and dictionary attacks respectively on the password file created from EXTRACT.EXE. Other security implications include the fact that there are a number of older bindery calls intended for Netware 3.x that may be used against Netware 4.x, and these bindery calls could allow certain security measures to be circumvented. While verifying that the same algorithm from Netware 3.x is being used for Netware 4.x, it was discovered that by performing a verify password call you could dictionary or brute force attack an account on a Netware 4.x server. By default, intruder detection is turned off on a freshly loaded Netware 4.x server. If bindery emulation is being used, a "verify password" call can be used to check whether a user account exists, and whether a guessed password is correct. A number of examples of programs used for logging in can adapted over to perform this type of attack. It has been reported that KNOCK.EXE has been used by some hackers to gain access to a Netware 4.x server, and I am aware of one development company of Netware utilities that had discovered the same thing. To be included in the next version of Pandora is INTRUDE.EXE, which can brute force determine user accounts as well as passwords. To use INTRUDE.EXE you can be logged in, even with minimal rights, but you will not need to be logged to use it. . o O o . [ Summary ] . o O o . Pandora can be used by an intruder (or an adminsitrator) in the following fashion to break in (or to determine vulnerability): - Use INTRUDE.EXE (when available) to determine common user accounts. If none are found, they can be brute forced. - Use INTRUDE.EXE (when available) to determine passwords. These can be done using either a dictionary or brute force attack. Any account could be attacked, including Supervisor (if it exists) or Admin. - By exploring using NLIST, NetAdmin, and by trying different accounts, determine an account that has read/write access to SYS:SYSTEM. - If BACKUP.DS exists, it can be copied off of the server. - By exploring the NCF files it should be possible to determine the remote console password, or possibly exploit the read/write access to an NCF file to gain console access. - Once console access is gained, using Novell's DSMAINT a fresh BACKUP.DS can be created and copied down. - BACKUP.DS can be converted into the original NDS files using CONVERT.EXE. - The NDS files can have EXTRACT.EXE run against them to create the PASSWORD.NDS file. - CRYPTO.EXE or CRYPTO2.EXE can be run against PASSWORD.NDS to do either a brute force attack or a dictionary attack to obtain additional passwords. For the intruder, this is safer since these attacks can occur offline. . o O o . . . . . . . . . o O o . Simple Nomad - Nomad Mobile Research Centre thegnome@nmrc.org - http://www.nmrc.org June 27, 1997