TTPwire Vol. 1 · MITRE ATT&CK·Tagged

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F5 Labs

De-icing IcedID: Decompression and Decryption Methods Explained in an IcedID Attack

2019-09-04 · Read original ↗

ATT&CK techniques detected

4 predictions
T1140Deobfuscate/Decode Files or Information
100%
“: decryption and decompression script once the script is run, the decrypted and decompressed data are shown in figure 9. figure 9 : decompressed and decrypted data from the icedid webinjects file the next step in this process is to convert the decrypted and decompressed data file…”
T1204.002Malicious File
84%
“de - icing icedid : decompression and decryption methods explained in an icedid attack icedid is a well - researched banking trojan. for this analysis, f5 researchers zeroed in on how its decompression method works. - in this article, we provide the code with which to analyze the…”
T1027.001Binary Padding
52%
“” and compression methods. figure 5 shows the search of value 0x8, which stands for deflate, which is a lossless data compression file format. this information is valuable to the malware so it can use the right decompression method in order to decompress and load the webinjects i…”
T1505.003Web Shell
41%
“decrypt the webinject files, we can take the first four bytes, reverse their order, and use them as the initial rc4 key to decrypt the webinject files. in the above example our key will be ‘ \ xe3 \ x2d \ x88 \ xec ’. now that we have the key, we can decrypt the first stage. afte…”

Summary

We detail the steps for decrypting and decompressing IcedID webinject files, enabling researchers to analyze IcedID samples and pull out target and web injection files.