Magnet Forensics is running a weekly forensic CTF. More information can be found on their blog. It is a fun way to practice, so let’s get to it!
|Week 1||Week 2||Week 3||Week 4||Week 5||Week 6||Week 7||Week 8||Week 9||Week 10|
New image for December! It can be found here. This is a memory image, and this week has multiple questions. Note: I may jump between Volatility 2.6 and 3 as I’m playing around.
Q1: What is the IPv4 address that myaccount.google.com resolves to?
First I pinged myaccount.google.com. I was pretty sure the same resolution would not be it, but it was worth a try. Next, I looked for active connections. I found a few owned by Google, but no indication that they belong to “myaccount”.
I looked for a way to extact the DNS cache, but could not find any tool or tip that worked for me. After a long while running down some research leads, I decided to try a search for any Google IP addresses around “myaccount.google.com”. Hopefuly this would get me the DNS cache, even if I don’t know the structure.
$ strings memdump-001.0.mem | grep -B 5 -A 5 myaccount | grep 172\. 220.127.116.11 18.104.22.168le.com0
In the command above I am using strings on the memory image, and returning 5 rows before and after the hit for “myaccount”. Then I search for 172, which is what I guess is the first octet of a Google IP address.
Tried 131, but failed. Trying
22.214.171.124 and BING! Success.
Really looking forward to the writeup for this question!
Q2: What is the canonical name (cname) associated with Part 1?
I’m not sure if I did this one as intended, but I queried the current state of Google DNS.
$ dig myaccount.google.com ;; DiG 9.16.1-Ubuntu myaccount.google.com ;; global options: +cmd ;; Got answer: ;; HEADER opcode: QUERY, status: NOERROR, id: 16677 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1 [SNIP] ANSWER SECTION: myaccount.google.com. 2674 IN CNAME www3.l.google.com. www3.l.google.com. 283 IN A 126.96.36.199 [SNIP]
www3.l.google.com and BING! Success.
I spent a lot of time looking for DNS cache in memory and didn’t find anything. I tried to look a bit at the structure that was returned during search. This is something I really want to look into more in the future. I’m excited to see what everyone came up with, and maybe there is an easy solution I didn’t find.