Authored by Margit Hazenbroek At Fox-IT (part of NCC Group) identifying servers that host nefarious activities is a critical aspect of our threat intelligence. One approach involves looking for anomalies in responses of HTTP servers. Sometimes cybercriminals that host malicious servers employ tactics that involve mimicking the responses of legitimate software to evade detection. However, … Continue reading The Spelling Police: Searching for Malicious HTTP Servers by Identifying Typos in HTTP Responses
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Popping Blisters for research: An overview of past payloads and exploring recent developments
Authored by Mick Koomen Summary Blister is a piece of malware that loads a payload embedded inside it. We provide an overview of payloads dropped by the Blister loader based on 137 unpacked samples from the past one and a half years and take a look at recent activity of Blister. The overview shows that … Continue reading Popping Blisters for research: An overview of past payloads and exploring recent developments
From ERMAC to Hook: Investigating the technical differences between two Android malware variants
Authored by Joshua Kamp (main author) and Alberto Segura. Summary Hook and ERMAC are Android based malware families that are both advertised by the actor named “DukeEugene”. Hook is the latest variant to be released by this actor and was first announced at the start of 2023. In this announcement, the actor claims that Hook … Continue reading From ERMAC to Hook: Investigating the technical differences between two Android malware variants
Approximately 2000 Citrix NetScalers backdoored in mass-exploitation campaign
Fox-IT (part of NCC Group) has uncovered a large-scale exploitation campaign of Citrix NetScalers in a joint effort with the Dutch Institute of Vulnerability Disclosure (DIVD). An adversary appears to have exploited CVE-2023-3519 in an automated fashion, placing webshells on vulnerable NetScalers to gain persistent access. The adversary can execute arbitrary commands with this webshell, … Continue reading Approximately 2000 Citrix NetScalers backdoored in mass-exploitation campaign
One Year Since Log4Shell: Lessons Learned for the next ‘code red’
Authored by Edwin van Vliet and Max Groot One year ago, Fox-IT and NCC Group released their blogpost detailing findings on detecting & responding to exploitation of CVE-2021-44228, better known as ‘Log4Shell’. Log4Shell was a textbook example of a code red scenario: exploitation was trivial, the software was widely used in all sorts of applications … Continue reading One Year Since Log4Shell: Lessons Learned for the next ‘code red’
I’m in your hypervisor, collecting your evidence
Authored by Erik Schamper Data acquisition during incident response engagements is always a big exercise, both for us and our clients. It’s rarely smooth sailing, and we usually encounter a hiccup or two. Fox-IT’s approach to enterprise scale incident response for the past few years has been to collect small forensic artefact packages using our … Continue reading I’m in your hypervisor, collecting your evidence
Sharkbot is back in Google Play
Authored by Alberto Segura (main author) and Mike Stokkel (co-author) Introduction After we discovered in February 2022 the SharkBotDropper in Google Play posing as a fake Android antivirus and cleaner, now we have detected a new version of this dropper active in the Google Play and dropping a new version of Sharkbot.This new dropper doesn't … Continue reading Sharkbot is back in Google Play
Detecting DNS implants: Old kitten, new tricks – A Saitama Case Study
Max Groot & Ruud van Luijk TL;DR A recently uncovered malware sample dubbed ‘Saitama’ was uncovered by security firm Malwarebytes in a weaponized document, possibly targeted towards the Jordan government. This Saitama implant uses DNS as its sole Command and Control channel and utilizes long sleep times and (sub)domain randomization to evade detection. As no … Continue reading Detecting DNS implants: Old kitten, new tricks – A Saitama Case Study
Flubot: the evolution of a notorious Android Banking Malware
Authored by Alberto Segura (main author) and Rolf Govers (co-author) Summary Flubot is an Android based malware that has been distributed in the past 1.5 years inEurope, Asia and Oceania affecting thousands of devices of mostly unsuspecting victims.Like the majority of Android banking malware, Flubot abuses Accessibility Permissions and Servicesin order to steal the victim's … Continue reading Flubot: the evolution of a notorious Android Banking Malware
Adventures in the land of BumbleBee
Authored by: Nikolaos Totosis, Nikolaos Pantazopoulos and Mike Stokkel Executive summary BUMBLEBEE is a new malicious loader that is being used by several threat actors and has been observed to download different malicious samples. The key points are: BUMBLEBEE is statically linked with the open-source libraries OpenSSL 1.1.0f, Boost (version 1.68). In addition, it is … Continue reading Adventures in the land of BumbleBee