Author Archives: zam

Analyzing Phishing Email – Word XML File Analysis

Recently I’ve observed a phishing mail as below:
https://www.virustotal.com/#/file/cf027dd938f1a268f45f2ea786dc538ab47f35006fb12d0b64e0867bccf789c0/detection – clean

The file seems to be clean per VT. Interestingly, on details sections, found 2 URLs on OpenXML Doc Info.

To search for these URLs, first you’ll need to rename the Word doc file to compressed zip file. E.g. sample.doc to sample.zip.

Then, extract the zip file. The URLs can be found inside file document.xml.rels (~/sample_folder/word/_rels/):

Its may look simple if you know which & where the file to be look at.

I’m thinking; what if we can search for all the URL/hyperlink in the XML files content of the Word document, without actually having to open it one-by-one.

To do that, we’ll using zipdump, re-search (together with reextra) Python script tools by Didier Stevens:

  • zipdump
  • re-search
  • reextra
  • Download the Python scripts mentioned above in one place. Then, executed this command below:

    Command above will search the content of the zip file & extract/applied regex searching for URLs.
    As you can see below, these is all the URLs that contained in the Word doc:

    Check bulk IP for reverse DNS (rDNS)

    Recently I’ve encounter list of IPs that are related to CoinHive. So I want to check for these IPs DNS. We can do that by using dig command to perform reverse DNS (rDNS).

    Reverse DNS (rDNS) is a method of resolving an IP address into a domain name, just as the domain name system (DNS) resolves domain names into associated IP addresses.

    I found this script at this site:

    Just save this code above in your Linux/*nix machine, and run this command as below:

    The result should be like this:

    Import & export installed Cygwin packages

    Recently I’ve changed my workstation to new one. Previously I’ve installed bunch of Cygwin packages on my old workstation.

    So I thought; can I somehow migrate my installed Cygwin packages from my old workstation to new workstation?

    The answer is yes. Follow me along to this wonderful journey XD

    First you’ll need to save list of what you have installed on your Cygwin on old workstation.
    To do this, open the Cygwin terminal/console & run this command below:

    Its basically dump a list of installed Cygwin packages in your workstation & save it to text file with comma-separated.

    Next, go to your Cygwin home folder (commonly locate at “C:\cygwin64\home\“), open the “cygwin_packages.txt” file that we save before & copy all the content inside the text file.

    Next, at your new workstation, ensure you have downloaded the latest Cygwin installer “setup-x86.exe” (32-bit) or “setup-x86_64.exe” (64-bit).

    Then, open your Windows cmd & change you directory to where you save the Cygwin installer. E.g. for my case here, I save it in my Downloads folder “C:\Users\Zam\Downloads>”.

    Then, run this command below on your Windows cmd; replacing/inserting the content of cygwin_packages.txt inside the double-quote as below:

    You should see the Cygwin GUI opened & UAC requesting permission pop-up:

    Click “Yes”, go through “Next” button & wait until the installation finished.

    Analyzing Oracle WebLogic attack

    Recently we received an alert from our WAF related to an attack towards out environment.
    Further review of the alert found that the attacker is using Oracle WebLogic RCE Deserialization Vulnerability (CVE-2018-2628).

    We observed that the attacker included some sort of PowerShell command in their request:

    Seems like the PowerShell command is using Base64 encoding for obfuscation.
    I use https://gchq.github.io/CyberChef/ to decode the Base64:

    Seems like it tried to fetch DL.php file at http://111.230.229.226/images/test/DL.php.
    Lets try grab that file:

    Hmm.. Error 404..? Is it true error?
    Or did we missing something here?

    Lets analyze the command carefully:

    We can see the attacker is assigning/using specific User-Agent when fetching the file.
    That’s why when we try to wget/curl the file directly, it failed.

    So what we have to do is we set the User-Agent exactly same when fetching the file.
    In this case, I’m using curl to fetch the file:

    Now see? Previously if the fetch the file without the User-Agent, it will failed/error 404.
    Again, we see another set off Base64 encoding here.

    But what is it?
    I’m not an expert to explain this, but TL;DR, it convert Base64 encoded string to a memory stream and executes it. I guess ¯_(ツ)_/¯

    So, to see what happen if this command executes, we can use this Python script below to decode it.
    With this script, we can basically see what are those Base64 are doing.

    Take the Base64 at above, paste it at encoded parameters as example below:

    Save the script and run the Python script as command below:

    This will save all the output from your CMD to text file for easier to ready.
    P/S : Your can rename output_DL_php.txt to any filename that you want.

    Let’s see whats inside the text file:

    As you can see, the command is doing bunch of stuff that I’m lazy to explain 😉
    Hope you enjoy reading this.

    IOCs:

    References:
    https://gist.githubusercontent.com/strazzere/5faa709a3db9e1dcf3b5/raw/42b98a918bac3725934bcfa3087ac5936d9b88d1/decrypt.py
    http://threat.tevora.com/5-minute-forensics-decoding-powershell-payloads/

    Wargames 2017 – Challenge 12 : ezfile sharing

    Challenge 12 : ezfile sharing

    question for challenge 12

    and the hint for this challenge:

    hint for challenge 12

    one of our teammate was fuzzing around the website and found “.git” folder.
    seems related to the hint.
    we try to browse the folder/path:

    .git folder/path

    as a “layman” person (please guys, don’t try this at home. or any other place. wkwkwkwk), I’ve gone too far by downloading all the git folder (recursively):

    download all git folder content

    lets see what git -help can provide us with info:

    git help menu

    hmm.. lets see if “git show” can provide any clue…

    and.. profit! XD

    so the flag is: “wgmy:{AdminGitGudPlease}”

    Wargames 2017 – Challenge 9 : unreachable

    the question is:

    question for challenge 2

    question for challenge 2

    and the hint given to us:

    hint for challenge 2

    hint for challenge 2

    so… RFC 792 – something related to ICMP/ping yada yada
    so we open the pcap file in Wireshark, view only ICMP protocol:

    open pcap using wireshark & then filter ICMP only

    we can see ICMP traffic involving 2 IPs; 192.168.1.8 & 192.168.1.10
    after digging around, I find out there is some “unique differences” at ping identification number; offset 0010. this involving IP 192.168.1.8.

    lets use tshark to see it clearly:

    use tshark & grep offset 0010

    as noted in the hint above;
    “he is tracing backwardly.”

    the flag is: flag_is_p!ngp0ng~
    but actually…. the flag is: p!ngp0ng~

    Shell hiding in image files

    One day, we noticed strange GET request towards our JBoss server:

    From the request above, you’ll quickly noticed that this attack leveraging Apache Struts vulnerability from CVE-2017-5638.

    The request tried to execute command below:

    “-O” : writes the documents to file.
    “-” : if is used as file, documents will be printed to standard output, disabling link conversion.
    “-q” : quiet (no output)

    As you see, it tried to fetch image (jpeg file) from 91.230.47.41. Seems normal right?
    We fetch the file & take a look at the jpg file:

    ASCII?? Not JPEG?? hmm..
    Here’s whats inside the “logo.jpg” file:

    We noticed there are several other file fetched; possibly a config file & bin file.
    Let’s fetch those file!

    Here is the config file:
    http://91.230.47.41/pics/kworker.conf

    Not sure it is. Maybe bin file to run a process:
    http://91.230.47.41/pics/kworker

    Lets see if the file is packed:

    Yup. So lets unpacked the file using UPX:

    http://91.230.47.41/pics/kworker_na

    Overall, looks like the attacker want to hack our servers & turn it into his own crypto currency mining machine.
    Typical behavior of attack we see in this time where the crypto currency is rising. People hack to make profit. 🙂

    Here the MD5 for file above:

    Configuring proxy for APT in Ubuntu

    Recently, I have a problem where when I tried to update Ubuntu package via apt-get, it shows HTTP 401 proxy error related.
    Just a note, I’m running the VM using my office network which has a proxy servers.

    From this site;

    References :
    http://askubuntu.com/questions/257290/configure-proxy-for-apt
    http://askubuntu.com/questions/543616/why-does-add-apt-repository-now-fail-to-retrieve-keys-behind-my-proxy-server-bu