Ransomware & Entropy: Your Turn -> Solution
This is the image you can recover from the ransomed file I published in my last diary entry.
Let's use byte-stats to check the entropy of the ransomed file:
We don't see much difference between the overal entropy and the entropy of the buckets, but that's because it's a small file. Notice that only 3 buckets were used. The file is only 36KB, so let's use a smaller bucket size: 1024 bytes.
The smallest value for the entropy is 7.32... So we have something in this file that is not encrypted/compressed. Let's try to locate this:
The lower entropy appears to be around position 0x1000. Let's take a look:
Bytes before 0x1000 look random, while we see some patterns appearing after 0x1000.
FFDB is the JPEG marker for quantization tables. This should be preceded by a JPEG header, like this one: \xFF\xD8\xFF\xE0\x00\x10\x4A\x46\x49\x46\x00\x01\x01\x01\x00\x48\x00\x48\x00\x00
To recover the image, just create a new file with this JPEG header and append all bytes from the ransomed file starting at the FFDB marker (position 0x1000).
What is this image? It's a thermal image of my MacBook 12" with the processor running "hot". The processor is located where you see the yellow/orange spot. The color indicates it's around 39°C. That's around 312°K and 102°F.
Didier Stevens
Microsoft MVP Consumer Security
blog.DidierStevens.com DidierStevensLabs.com
IT Security consultant at Contraste Europe.
Comments
Anonymous
Dec 3rd 2022
9 months ago
Anonymous
Dec 3rd 2022
9 months ago
<a hreaf="https://technolytical.com/">the social network</a> is described as follows because they respect your privacy and keep your data secure. The social networks are not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go.
<a hreaf="https://technolytical.com/">the social network</a> is not interested in collecting data about you. They don't care about what you're doing, or what you like. They don't want to know who you talk to, or where you go. The social networks only collect the minimum amount of information required for the service that they provide. Your personal information is kept private, and is never shared with other companies without your permission
Anonymous
Dec 26th 2022
9 months ago
Anonymous
Dec 26th 2022
9 months ago
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
Anonymous
Dec 26th 2022
9 months ago
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> nearest public toilet to me</a>
<a hreaf="https://defineprogramming.com/the-public-bathroom-near-me-find-nearest-public-toilet/"> public bathroom near me</a>
Anonymous
Dec 26th 2022
9 months ago
Anonymous
Dec 26th 2022
9 months ago
https://defineprogramming.com/
Dec 26th 2022
9 months ago
distribute malware. Even if the URL listed on the ad shows a legitimate website, subsequent ad traffic can easily lead to a fake page. Different types of malware are distributed in this manner. I've seen IcedID (Bokbot), Gozi/ISFB, and various information stealers distributed through fake software websites that were provided through Google ad traffic. I submitted malicious files from this example to VirusTotal and found a low rate of detection, with some files not showing as malware at all. Additionally, domains associated with this infection frequently change. That might make it hard to detect.
https://clickercounter.org/
https://defineprogramming.com/
Dec 26th 2022
9 months ago
rthrth
Jan 2nd 2023
8 months ago