SE16N_BATCH is a very powerful and dangerous program. You can use it to run SE16 queries for large datasets in batch mode and later pick up the results from the spool.
But it can also be misused to fetch data that you are not authorized to see, but a batch user can see.
Good use
For example you need a lot of records from BSEG:
This might fail online. If you run it in batch mode, you can simply pick up the spool later with the needed data:
Misuse
The program can be used for hacking purposes as well. Suppose you want to get all user password hashes. SE16N for USR02 is blocked. Now run the program in batch (not with your own user, but with a batch job user with rights to read USR02 data). Now all data is available in the spool for the hacker….
In the user exit code, you can put in your own stuff.
As hacking example: copy function module PASSWORDCHECK and the screen that belongs to it to your own ZPASSWORDCHECK.
Modify the screen logic a bit. This is the original code:
Now change the code: the password is always reported back as ok. And the user input you catch in the field password is yours: you can mail it or store it somewhere for you to pick up later.
Put the altered code in the user-exit with logic:
IF SY-UNAME = 'target user name' and not capture before.
CALL Z function ZPASSWORDCHECK.
Store capturing.
Set capture flag.
ENDIF.
This looks as follows at runtime:
Many end users (and even auditors) will enter their password without thinking twice.
Alternatively you can use function module POPUP_GET_USER_PASSWORD as a basis for your copy: this has also clear text password:
The password field can be stored.
This has the following look and feel:
Detection and protection
It is wise to shield off this user exit from improper use and to yearly check the content of what is inside this user exit.
SCI and ATC are very powerful code scanning tools (see blog and blog). Unfortunately you cannot apply it to standard SAP and add-ons.
Analyzing standard SAP code is the responsibility of SAP, and they take good and secure code (since they provide good code, it is weird they don’t allow everybody to scan their code…). Unfortunately a lot of add-on providers do not.
The blog will explain how to scan code of standard SAP and mainly on add-ons.
Questions that will be answered are:
What is the background on not being able to scan standard SAP and add-on code?
Can I truly scan the code of a new OSS note 7 days?
How can I work around these restrictions and still scan the code of an add-on?
Background
The background of not being able to scan standard SAP code is explained in OSS note 1986391 – Using SLIN/SCI to check SAP standard objects. This note also explains you can scan OSS notes and transports for 7 days. After that time it is no longer possible. Unfortunately this rule also applies to add-ons.
Why run SCI on add-ons?
Why would you want to scan add-ons? Add-ons come with various quality levels. Ranging from very well written with much attention to performance and security. Some add-ons are full of performance issues and full of security leaks. Some are even allowing full dynamic read SELECT and UPDATE statement without any authorization check. This is heaven for a hacker!
The below method is meant for scanning these poor add-ons using the SCI tool for performance, robust coding and security.
When you run the SCI tool on an add-on by selecting package or development object, you get the message that it does not contain any objects:
This is because your selection is first scanned for standard SAP and add-on objects. These are removed. So the result set is empty.
Goto transaction SE24 and select class CL_CI_OBJECTSET. Now select method BUILD_TADIRSET and display the code:
Put a break-point as statement if ENABLE_CI ne ‘X’.
Now start the SCI tool again. If the debugger stops at this statement, use debug and replace to change the content of ENABLE_CI to ‘X’. Now the skipping of SAP and add-on objects is not done. SCI will scan the code. It will still not use SLIN. But these are minor checks.
Changing directly data on an SAP table is the IT admin and IT auditors worst nightmare. This blog will show you the ways it can be done.
Questions that will be answered in this blog are:
How can I directly edit tables?
How can I prevent direct table editing?
How can I detect direct table editing?
Overview of methods
Function module SE16N_INTERFACE
Debug & replace
SE16N_EMERGENCY mode
Re-enable &sap_edit for SE16N
Direct table editing method 1: function module SE16N_INTERFACE
This method is available in the SAP S4HANA system. Start with transaction SE37 and key in function module SE16N_INTERFACE. Now press the test button. In this demo we will change dates for sales order table VBAK. In the SE37 test screen enter table VBAK and very important put X in the I_EDIT and I_SAPEDIT fields.
Now hit execute and voila: you are in direct edit mode:
Now we change a few values (date to the year 2027…) and press save:
Data is changed.
Detection of this method: audit logging. In audit logging you can see the user started SE37 and then used report RS_TEST_FRAME_CALL, but you cannot see which module was done, neither is the data change logged.
Prevention of this method:
Debug/replace is needed to change the data: don’t hand out debug/replace.
Deny access to this function module.
Direct table editing method 2: debug/replace
Start transaction SE16 and show the data of the table to edit. Example in this case VBAK data:
Now select a line and put /h for debugging in the command line input. Press enter and the debug screen will open. Double click on the SY-UCOMM field:
In the variables screen now change the value ENTR (for the enter command you gave) to value AEN2 (command to change). Make sure the value is accepted. Now hit F8 to continue. And voila: edit mode:
Change the values (dates in this example) and press save:
How to detect this method: in the SAP audit log (activation of audit log is explained in this blog) show the change in debug/replace mode:
Prevention of this method: don’t hand out debug/replace rights.
Direct table editing method 3: SE16N emergency mode
In newer SAP netweaver releases there is a new SE16N emergency mode which can be started with transaction SE16N_EMERGENCY. Read all the details in this special blog on this topic.
Direct table editing method 4: re-enable &sap_edit again in SE16N and use it
Apply OSS note 1468636 – CO-OM tools: SE16N: Use of &SAP_EDIT. This seems old, but it is still valid for all S4HANA releases as well. After the note is installed run program RKSE16N_EDIT and activate the function:
Now start SE16N and select your inputs. Before hitting the execute button, enter the command &sap_edit:
Only now press execute. The result is fully editable table.
A lot of basis and ABAP people feel protected by the ABAP keys and object keys for standard SAP changes. They have to be called off at SAP marketplace keys section.
Let me already give away the clue: since quite some time there is a KeyGen for ABAP and object keys. The protection is gone.
This blog will answer following questions:
Where can I download the ABAP keygen?
How to run the ABAP keygen?
How should I protect my system from unwanted ABAP changes?
S4HANA does not use developer keys and object keys any more, how should I protect my S4HANA system from unwanted ABAP changes?
Where can I download the ABAP keygen?
Google for SAP IWR Object key generator. Or click here for a copy:
Running the executable is simple. But you need to run it in Windows 7 compatibility mode.
Fill out the data and hit generate…. that’s all.
The use of this tool is at your own risk. Most admins don't like you to use this tool at all.
The whole idea of this blog is to show not to rely on the developer key procedure.
How should I protect developments?
The best way to protect your development is to carefully grant the S_DEVELOP privilege. Only give it to the right people and only give it to develop Z* range of code.
Deletion of old developer keys is still relevant. Read the dedicated blog on deletion of developer keys.
S4HANA developer key
The title is a bit misleading. In S4HANA there are no developer keys and object keys any more.
If the code is ok, set the break-point at ABAP command AUTHORITY-CHECK:
Now click on the Start Script button.
End result: you can execute the program without any issues.
Explanation of the method
What has happened here? The debug scripting is nothing more then fast automation. The developer could have manually bypassed all the multiple authorization checks in this program. Now he lets the script take care: the coding of the script simple changes the SY-SUBRC value after any break-point (which is reached at statement AUTHORITY-CHECK) to 0, which is green light: pass.
Prevention
If you don’t want this to happen in your system there are 2 main measures to take:
Remove debug & replace authorization from all non-ABAP developers in a development system and remove debug & replace from all non-development systems for all users
Make sure you tell the ABAP developers that you are aware of this script. You cannot prevent them from running it, but you can tell them that if you find out it can have severe consequences.
This blog series will explain the process of hacking SAP password hashes: also know as SAP password hacking. The process of hacking will be explained and appropriate countermeasures will be explained.
In this fourth blog we will continue with more complex attacks on the SAP password hashes and will also explain more preventive measures.
For the first blog on attacking the SAP BCODE hash click here.
For the second blog on attacking the SAP PASSCODE has click here.
For the third blog on attacking the SAP PWDSALTEDHASH has click here.
Questions that will be answered in this blog are:
How does the rule based attack work?
How to use the rules on found passwords?
Where to find good rule books?
The rule based attack
The dictionary rule book attack is using the dictionary as input and then applies rules to the dictionary to generate a new password candidate.
Example words we will use are Password and Welcome.
Examples of apply some rules:
Replace a with @ will give P@ssword
Replace o with 0 will give Passw0rd and Welc0me
Replace s with $ will give Pa$$word
Replace l with ! will give We!come
All rules above combined will give P@$$w0rd and We!c0me
For full list of possible rule syntax see Hashcat site on rule-based attack.
Suppose we have guessed one correct password for one user. He made the password Welcome1!.
Now we will construct some rules:
Replace e with 3, rule will be se3
Replace l with 1 and l with !, rules will be sl1 and sl!
What has happened here? Why is this found now, and not before with the se3 rule, which should substitute the e with 3? Pretty simple: replace e with 3 in word Welcome1! will give W3lcom31!. So it replaces all and not first one. This is there background of having many rules.
Huge rulesets
With the Hashcat download you get a special directory called rules. Here there are some big rulesets available.
The nicest one is the RockYou list of rules. This is constructed based on the RockYou password list hacked in 2009 where 32 million passwords leaked. Based on English dictionary somebody has constructed the rules to come to most of these passwords.
Effectiveness of the attack
The effectiveness of the rule based attack is quite high. If you have found 1 password, you just run the complete ruleset of one of the huge lists to find multiple variations. People are not so inventive and creative. You will be surprised on the amount of password variations you find on the following words:
Welcome
Summer
Winter
Password
Apple
Android
Google
Hackers don’t start with the full dictionary. They start with the top 1000 words and apply many rules to them. From the passwords found they will start to derive patterns of the users. Any new password is processed through many new rules to generate candidates with higher potential.
The name and or abbreviation of a company is word number 1 to add to the favorite word list.
Further optimization of the attack speed
For optimizing the attack speed, read the fifth blog on SAP password hash hacking here.
Prevention measure 1: frequent change and large change per time
Many companies have implemented a more faster cycle of password changes. In the past once per year was common. Nowadays 60 to 90 days is more common practice. Set this in profile parameter: login/password_expiration_time.
More important is to make a larger change per time the password changes. This is to avoid the rule-attacks explained above to become very effective. How many people just simply change and increase single digit in password? Or increase the special with the next one on the keyboard. Set the profile parameter login/min_password_diff to sufficiently high value of 3 or more.
Prevention measure 2: length
Explain to your users that length is more important than complexity by using this famous explanation:
Prevention measure 3: stronger hashes
Stronger hashes simply take more time to crack. To set stronger hashes, read this dedicated blog.
Next blog on password hacking
The fifth blog on password hacking is about optimizing the attack speed. Read on in the blog. And the blog on extended word lists.
This blog series will explain the process of hacking SAP password hashes: also know as SAP password hacking. The process of hacking will be explained and appropriate countermeasures will be explained.
In this third blog we will continue with more complex attacks on the SAP password hashes and will also explain more preventive measures. Now we focus on the SAP PWDSALTEDHASH hash.
For the first blog on attacking the SAP BCODE hash click here.
For the second blog on attacking the SAP PASSCODE has click here.
For follow up blog on improving attack speed by applying rule-based attack, click here. And the blog on optimizing the attack. And the blog on extended word lists.
Questions that will be answered in this blog are:
How to get the PWDSALTEDHASH codes?
How does the dictionary attack work?
How does the dictionary combination attack work?
How does the dictionary with mask attack work?
What more can I do to prevent a password attack?
Getting the PWDSALTEDHASH codes
The testusers 1 to 5 have been given a new password and the security admin has done its job. This is what you see in USR02:
Double clicking on a line and scrolling down will give you the PWDSALTEDHASH field content:
Getting many is too much work. For this you can use code of the program ZFETCH_PWDSALTEDHASH below:
*&--------------------------------------------------------------------**& Report ZFETCH_PWDSALTEDHASH*&--------------------------------------------------------------------*REPORT ZFETCH_PWDSALTEDHASH.DATA: LV_USR02 TYPE USR02.DATA: LV_STRING TYPE STRING.SELECT * FROM USR02 INTO LV_USR02 WHERE PWDSALTEDHASH NE SPACE.CONCATENATE LV_USR02-BNAME '
The output for our testusers is now:
You need to save the part from {x-issha etc in a new file. The user ID in front is not needed. It is just needed in case you decrypt a password from a hash to go find the user ID.
The dictionary attack
We still assume that there is a very strict policy on strong password:
Minimum length 10
Minimum 1 upper, lower, digit and special
Since the admin has cleaned up the BCODE we have no idea on the first 8 characters now.
The trick we will use is the dictionary attack. We assume some of the users will use a password with the following rule:
Take a word
Capitalize first letter, rest is small
Add a digit
Add a special character
As input file for this attack we take all word from the Webster Dictionary: webster dictionary file.
We now go back to our Hashcat directory on C:\HC and give following command:
Command explanation: attack mode 6 for dictionary attack and 10300 for SAP PWDALSTEDHASH format.
And now hashcat is showing is parallelization power:
To test all the combinations on the 5 users only 30 minutes are needed, with almost 200.000 tries per second.
2 passwords were found: TESTUSER1 with password Theobald1! and TESTUSER5 with password Tetrazotization5{.
Especially the last one is striking: this is normally not considered a simple password: Tetrazotization5{. But because it appears in a dictionary it is relative simple to retrieve.
Combination attack with dictionary
To really show the speed, we will now perform the combination attack explained in the previous blog again. We will use the dictionary in combination with the popular extension file. Command to give:
It runs for 4 hours with about 200.000 guesses per second:
And it finally finds the last password: TESTUSER4 with Organoid1@#
Dictionaries
The example above is just one dictionary. Also think about dictionaries with names of persons, football clubs, cities and countries, etc. Largest dictionary so far is called the Wikipedia dictionary. It is about 250 MB large and contains all the unique words used on Wikipedia.
Preventive measures
Preventive measure 1: user education
Educate your users not to take a dictionary word directly and only add a digit letter.
Especially power users, like basis and user administrators, should really receive this education. Don’t assume they know. 90% of them does not, or even hands out passwords like Welcome2018!
Preventive measure 2: extra strong passwords for background and power users
You can set extra strong password requirements for background users and power users (basis and user administrators). This can be done by setting up specific security policies. This is explained in this blog.
Preventive measure 3: stronger hashes
By creating stronger hashes, the attackers need more time. It will not stop them, but slow them down. Read more on setting stronger hashes in this dedicated blog.
Next blog
The next blog will focus on rule based attack mode, which is one of the most effective methods.
This blog series will explain the process of hacking SAP password hashes: also know as SAP password hacking. The process of hacking will be explained and appropriate countermeasures will be explained.
In this second blog we will continue with more complex attacks on the SAP password hashes and will also explain more preventive measures. Now we focus on the SAP PASSCODE hash.
For the first blog on attacking the SAP BCODE hash click here.
Questions that will be answered in this blog are:
How to attack the PASSCODE from the BCODE?
How does the hybrid mask attack mode work?
How does the combination attack mode work?
What more can I do to prevent a password attack?For follow up blog on hacking SAP PWDSALTEDHASH, click here.
For follow up blog on improving attack speed by applying rule-based attack, click here. And the blog on optimizing the attack. And the blog on extended word lists.
How to attack the PASSCODE from the BCODE?
In the previous blog we have seen how easy it is to get the passwords from the BCODE. The BCODE is capturing the first 8 characters of the password in capital mode. The other characters of the password are not stored in the BCODE, but in the full PASSCODE. If the password is length 8 or below, you can already logon with the found BCODE password.
Now lets assume company password policy is:
Minimum password length is 10
Minimum 1 digit, 1 letter upper case, 1 letter lower case, 1 special
Pretty safe you might think.
We will use the previous 5 guessed test users. Their passwords from BCODE were: PASSWORD, LETMEIN, WELCOME, ILOVEYOU, STARWARS. We don’t know exactly which letters in the passwords are uppercase and which ones are lowercase. But we can make educated guess here, which we store in notepad file:
As you can see these are logical variations. Most people use password as they type: First letter in upper case, rest in lower case.
Getting the PASSCODE from USR02 table
We use one of the many methods to get the PASSCODE hash strings from the USR02 table:
And we put this into notepad file with user name and $ for separator:
Hybrid mask attack
What we will do is use a so called hybrid mask attack. This attack uses certain patterns.
The first pattern we will use is use the file with the BCODE guesses and at the end at a digit and special character.
To start the hacking process go to the CMD command prompt and proceed to the hashcat directory. Then key in this command:
Explanation of the command: 7800 means the hashes are SAP PASSCODE. Output goes to _found file. Input is the TestuserPassCodeHashes file. The text fie with the guesses is then combined with ?d?s. This means take every entry from the file and add first a digit, then a special. This will then try for example Password1!, Password2!, ….Password1@, Password2@, etc.
Result (after 1 min or so):
Password found: Password1! for testuser1. The output is in the output file. And the found hash is removed from the input file.
Hybrid mask patterns
Some patterns that can be used:
?l = letter, small caps
?d = digit
?s = special
?a = all possible input characters
If we continue with our example: we now will not scan for digit special combination but for any 2 or more characters. To do so: replace in the previous command the ?d?s with ?a?a.
After that we can run with ?a?a?a to find any combination with 3 characters at the end. Runtime: only 4 minutes:
Only when we add ?a?a?a?a for 4 characters runtime starts to increase to 6 hours:
After these runs we have found: Welcome123! for testuser3, IloveYou@9 for testuser4 and Starwars99*& for testuser5.
Combination attack mode
The above method is fast and almost always guaranteed to work. But is will only work for short extensions. There is even a faster way, but this method does not have full guarantee.
What we will do is construct a file with popular password extensions after the main word:
real file is much, much longer…
This file we will combine with the file of the already found words from the BCODE part. The combination of two files is called combination attack.
To start the hacking process go to the CMD command prompt and go to the hashcat directory. Then key in this command:
The attack mode 1 means combination attack to combine the two files.
After running this mode the Testuser2 password pops up: Letmein2018).
And yes: years in passwords are pretty popular.
End result
End result after all the different attacks:
And it really didn’t take long time. One overnight session is sufficient.
The real live sequence of cracking would be to start with the popular extensions to remove the quick wins. Then time can be spent on the hybrid mask attack: this attack goes faster when there is less input.
Preventive measures
Preventive measure 1: forbid simple password parts
By filling table USR40 you can forbid simple password parts to be used. Think about filling this table with words like:
Preventive measure 2: forbid display access to password tables
Forbid access to password tables. The hashes are stored in tables protected by the SPWD object. Don’t grant read access with S_TABU_DIS authorization object to this table group. Check via SUIM who currently has access and restrict it to only people you think really need it.
More information on the access protection can be found in OSS note 1484692.
Next blog
The next blog will explain on hacking PWDSALTEDHASH.
This blog series will explain the process of hacking SAP password hashes: also know as SAP password hacking. The process of hacking will be explained and appropriate countermeasures will be explained.
Questions that will be answered are:
Where are SAP password hashes stored?
Which software do I need to install for hacking the password hash?
How does the brute force method work?
How does the simple 10k most used password list attack work?
For follow up blog on hacking SAP PASSCODE, click here.
For follow up blog on hacking SAP PWDSALTEDHASH, click here.
For follow up blogs:
Improving attack speed by applying rule-based attack, click here.
SAP BCODE (oldest one and very weak): not to be used any more
SAP PASSCODE (less old, stronger than BCODE, but still weak): not to be used any more
SAP PWDSALTEDHASH (newest, strongest)
New SAP installations only use the newest method by default. Older system still might have stored older versions.
From user password to hash
When a users password is set initially or is changed is it hashed and stored in 2 tables:
USR02, which contains the current password
USRPWDHISTORY, which contains the history of the passwords
Older systems or wrongly configured systems store all the 3 password types mentioned above.
To start the password attack you need to get the user ID’s and hashes from the USR02 table.
Methods for getting this data (and many more):
SE11/SE16N table display
Write simple ABAP program
Database access on low level (HANA, Oracle, etc)
…. more creative methods….
For this weeks example we will use a couple of test users. The first 5 users are given simple passwords. The 6th user is given a fully random password.
The attack: from hash back to password
When you have the hashes all of the rest is now outside of the SAP system.
First step is to download a password cracking tool. A very good one is Hashcat.
Warning: this software might be considered as real hacking tool comparable to possessing burglary tools. Either only use on private laptop or after agreement of your local company security team.
Hashcat is based on GPU power and not CPU power. This means the speed of cracking depends on the quality and speed of your graphical card(s). Modern graphics card can have up to 4000 cores. Hashcat is written intelligently to use these 4000 cores via parallel processing or multiple cards.
Download the software from the site and unzip it on your local PC.
Hashcat requires for cracking BCODES the following format per line:
<<USERID>>$<<BCODE HASH>>
For the example above this results into the following file:
The brute force method
Let’s start by making a file with only TESTUSER6. This is stored in the file TestuserBcodeHashes.txt.
To start the hacking process go to the CMD command prompt, and proceed to the hashcat directory. Then key in this command:
Long command, but some part are simpler: -a 3 means brute force, -m 7700 means hashes are SAP BCODE hashes, file output and output, and very important the command to abort if the GPU temperature exceeds 80 degrees Celsius.
For full help options: go to the Hashcat website or key in Hashcat64 –help.
Result of this command is following screen:
The brute force attack will use some common pattern, but as you can see per pattern it takes about 16 hours (faster GPU means less time).
Guessing speed is at 57.000 tries per second, which is about 5 billion tries per day. Having a password with 8 random characters (26 letters, 10 digits, 33 specials) would take 69*69*69*69*69*69*69*69 = 513.000 billion options, meaning it would take 100.000 days.
Pretty good you would say. But nobody uses the brute force method.
Attacking with 10.000 most commonly used password list
If you have only letters, then the guesses for most users will be 26*26*26*26*26*26*26*26 = 208 billion only. By filtering out the hardly used q and x, it could even be 110 billion only.
Prevention 2: disallow the old hashes
Set parameter login/password_compliance_to_current_policy to 1 to forbid the old passwords to be used (in old systems this might require some testing before it is done in productive system, and changes of old passwords that are there for very long time).
Prevention 4: instructions to basis and authorization team to use the password generator for initial passwords
When generating new password: do use the password generator button. This will generate very complex password. Do use it.
Also you should make it known to basis and authorization team not to use simple and repetitive passwords like Welcome-2018 or Passw0rd! Soon you will see a pattern and can already guess new users passwords that they will select. Tell them to use the password generator.
Prevention 5: increase hash strength
You can increase the hash strength. This will make the attack last longer, since it simply takes more computing time to try stronger hashes. Read more in this blog.
Next blog
The next blog will explain on the hacking the SAP PASSCODE.
