This suggested that file contents were processed using code located at the offset of 4036B2. A more reliable way to detect the trojan with a network-based IDS is to scan packet contents for strings that are associated with the trojan's operation. In response to observed behavior, we installed and configured ircd-hybrid softwareIS on the Linux machine 172.16.198.129 to provide IRC services to the trojan. It'll copy two numbers into two registers and add them. To fill that knowledge gap, I have created this course. "TROJ_TASMER.B" URL: http://antivirus.com/vinfo/virusencyclo/default5.asp?VName= TROJ_TASMER.B&VSect=T. Portions of this document were submitted to SANS GIAC to fulfill GCIH certification requirements. by A. P. David. Sign up for my newsletter if you'd like to receive a note from me whenever I publish an article or embark on a project. The process of software reverse engineering and malware analysis often comprise a combination of static and dynamic analyses. This course is an introduction to Reverse . They don't have access to the source code of malware. Since cmp instruction set ZF flag in EFLAGS register je instruction will redirect execution to 0x8048448. Let's focus on the following a couple of assembly instructions. The same is true for malware analysis—by knowing the behaviors of a certain malware through reverse engineering, the analyst can recommend various safeguards for the network. The nature of this second string and its role in the decryption process became clearer later in our analysis process. Before we continue into the reversing part, Let's clear some basics ideas of this topic. URL: http://www.securityfocus.com/archive/75/167985. First, we write the code in a language like C, C++, etc. In the programming parts we will be writing programs that, Then, in the reversing part, we take the programs that we wrote and perform reverse engineering on it, In this way, you will, for the first time, really, How to compile and build executables and dynamic link libraries (DLL), Hiding shellcode payload in executable files, How to analyze and inspect memory of a running malware, Injecting Shellcode into running processes, Encryption of Payloads and Function Call String Parameters, Reverse Engineering and Malware Analysis Students, Programmers who want to know how Malware is created, Students planning on entering Malware Analysis and Reverse Engineering, or Penetration Testers as a Career Path, Students planning on entering Malware Analysis and Reverse Engineering or Penetration Testers as a Career Path. In this case the period in front of the "JOIN" command matches its "0A" hexadecimal counterpart, which represents the new line character. While our gus.ini file set the name to "mikey", the trojan's operator seems to be able to set it to an arbitrary value by manipulating contents of the gus.ini file. A strings snapshot of malware is considerably shorter than a complete listing of its disassembled code, but, of course, it is not as thorough. The purpose of other strings became a bit clearer after we analyzed contents of the gus.ini file. This section of the program reads characters one-by-one and aligns them in memory as adjacent bytes. 10 June 2000. This is a beginners course and targeted to those who are absolutely new to this field. The reason for waiting for the first fopen call before setting the second breakpoint was to let SoftICE calculate the absolute offset for the sub_405366 call's relative offset with respect to the trojan's runtime stack. To understand the decryption algorithm so that we could decipher strings embedded in our copy of srvcp.exe, we loaded the executable into the IDA Pro disassembler. I think you can read the code and determine what it does. "Re: unknown trojan (attached)." For a properly encrypted command to be honored by the trojan, the command needs to be prefixed by a proper password in each communication attempt. As we discussed earlier, at least two passwords are hard-coded into the program. This course is an introduction to Reverse Engineering for anyone who wants to get started in this field. The opcode for this instruction is 89 el. Focus on reverse engineering malware and perform binary auditing; . After that checking, we convert the input string to an integer using atoi() function. Methodology for Reverse-Engineering Malware This paper, written in 2001, once one of the first public documents that discussed tools and techniques useful for … Let's assume our input number is zero. A CrackMe is a small program designed to test a programmer's reverse engineering skills. In exploit development, we reverse a program and find vulnerabilities. TLDR 4 steps to using this guide: Do the Start Here Guide. The program also participated in periodic "PING" - "PONG" message exchanges as defined in the IRC protocol to ensure that the IRC client is alive. Initially we had concerns over stability of the program when running in VMware environment. The best way to understand malware is to be a Malware Developer. Similar functionality is available for Windows from the BinText program, which is freely distributed by Foundstone.FS BinText is a bit more flexible than most of its UNIX alternatives, and supports a range of advanced filtering options. "#Cracking4Newbies SoftIce Tutorial." This parameter's value is related to the value defined by the "CHANNEL" parameter through a common substring "soup". This is a beginners course and targeted to those who are absolutely new to this field. This was done in routine sub_404E78 that was invoked at offset 405435 soon after mutating the key prefix. First, there are still many unanswered questions about the particular trojan discussed in this write-up (srvcp.exe); positioning our findings as comprehensive analysis would be misleading at best. So it doesn't jump to the given address. 21 March 2001. jne stands for Jump if not equal. Manipulating DNS records in laboratory environment was trivial in this case; had the trojan's author hard-coded an IP address into the program, we would have had to configure local routing tables and network parameters to redirect traffic to our system. Here you can see I used two if statements. IDA Pro is one of the most widely used Disassembler for Reverse Engineering, Malware Analysis and Exploits analysis. ISBN: 9781800207974. If you want to master the art and science of reverse engineering code with IDA Pro for security R&D or software debugging, this is the book for you. In sometimes they can find vulnerabilities and week points of malware. Found inside – Page iIt’s also the heart of many single board computers like the Raspberry Pi. Gain the skills required to dive into the fundamentals of the ARM hardware architecture with this book and start your own projects while you develop a working ... Possibly the program's author can communicate with it via IRC messages to command the trojan to release the name so that the person may obtain it. Here is the disassembly of the main function. Knowing the general structure of the trojan from its disassembled code as well as from system and registry calls intercepted by Systernals tools, we were able to set SoftICE breakpoints on code sections that seemed particularly interesting. In this course we will learn IDA by solving Linux … It went quietly into the background, and besides adding the "srvcp.exe" process to the process list, did not register any behavior that could be observed with a naked eye. DR3 DataRescue. This is considerably less exhaustive than information provided by Snort, and most importantly lacks packet data payload. URL: http://www.winternals.com/products/monitoringtools/tcpviewpro.shtml. In an attempt to understand the algorithm used to obfuscate lines in the gus.ini file, we turned our attention to the second parameter that was passed to the decryption routine. (We manually highlighted relevant lines on the screen snapshot for emphasis.) Anti-virus vendors did not provide much information about this particular trojan, and later examination of virus databases disclosed lack of documented details regarding the trojan's capabilities, probably due to its relatively low profile. URL: http://vil.nai.com/villib/dispVirus.asp?virus_k=98569&EY=y. Detecting Malware Artifacts and Indicators of Compromise. That means there is a flag to set if two arguments are equal, also there is another flag to set if they are not equal. RFC1918 RFC 1918.URL: http://www.faqs.org/rfcs/rfc1918.html. If the user has given a number as an argument we continue the code. Vendors do not seem to agree on the name for this trojan, however. Notify me of follow-up comments by email. Joe Abrams. TM2 Trend Micro Virus Encyclopedia. Think of it as the Trojan Horse being the malware, the analyst being the soldier who initially inspected the horse, and the city being the network of computers. Malware may create temporary files as it executes, and delete them before the program exists. 7 November 2000. This book demonstrates how to write Python scripts to automate large-scale network attacks, extract metadata, and investigate forensic artifacts. There are rows of bytes. If we fid a one we can write an exploit to get the advantage of that vulnerability. Joe described this process as well, although his data offsets did not match ours, probably because of subtle differences in versions of the srvcp.exe executable. The "fight me, pussy" string matched the real name property of the trojan's IRC user as seen by the IRC server. Practical Binary Analysis is the first book of its kind to present advanced binary analysis topics in an accessible way. When we think about a compiled binary, it only contains mashing instructions as opcodes. The "daFuck" string, prefixed with "#", was the name of the IRC channel that the trojan joined. It is unclear whether the carrier program also installs a copy of the gus.ini file along with srvcp.exe. I will take you from zero to proficient level in analyzing malicious .NET and Java binaries. GREM-certified technologists possess the knowledge and skills to reverse-engineer malicious software (malware) that targets common platforms, such as Microsoft Windows and web browsers. In both instances the names were suggestive of abuse, and it is possible that we were looking at a mutated version of the program. However, the exception to this rule is the hosting operating system itself, which is only able to see traffic originating or targeting itself. Now the next instruction is jne. "new (?) Malware Analysis Threat Intelligence Reverse Engineering Bart Parys. The assembly routine was labeled in IDA Pro as "sub_4012C6" and started at the "text:004012C6" offset. One of our experiments was aimed at examining the nature of communications between a potential attacker and multiple instances of the trojan. Any individual looking forward to understand Reverse Engineering and Malware Analysis. This book is a starting point for developers interested in leveraging Ghidra to create patches and extend tool capabilities to meet their cybersecurity needs. A quick check showed 4 users online with the "Real Name" field set to "Im trojaned", one of which was my IP address. I'll focus on native . This indispensable guide illuminates the darkest corners of those systems, starting with an architectural overview, then drilling all the way to the core. 22 March 2001. As demonstrated in Figure 3-4 below, the trojan attempted to connect to port 6667 on the system it thought was irc.mcs.net. The executable can also be edited with a regular file editor to use a different registry key. We found freeware tools offered by Systernals to be very useful when monitoring the trojan's behavior. Think of it as the Trojan Horse being the malware, the analyst being the soldier who initially inspected the horse, and the city being the network of computers. This means that the operator trying to control the trojan would need to send a message to the IRC channel in the form "password command". They only know the how’s. The first thing that is usually needed is to clean the network and systems from being compromised. This is one of the ways to read in a whole line from the file, which is how the trojan reads in the gus.ini file line-by-line. In this example, we are using a Linux distribution. RFC1413 Michael St. Johns. In particular, machines would sometimes freeze and fail to start when SoftICE was activated. This could be a way to control the tenacity of the trojan's attacks, or to fine-tune its behavior on IRC channels. Intel Architecture Software Developer's Manual, Volume 2: Instruction Set Reference Manual. As you probably remember from previous chapters, Ghidra works with projects containing zero or more files. URL: http://www.activestate.com/Products/ActivePerl. URL: http://www.vmware.com/products/desktop/ws_faqs.html. 21 March 2001. Digital Marketing Course for Fitness Professionals- Enroll for FREE. Note that each actual character is followed by three null characters. IDA Pro is one of the most widely used Disassembler for Reverse Engineering, Malware Analysis and Exploits analysis.In this course we will learn IDA by solving Linux and windows CrackMe. I'll write more interesting stuff on these topics. As shown Figure 3-25, the trojan seems to rely on the ftp.exe program built into Windows for FTP-based file transfer capabilities. Contents of gus.ini seem to overwrite default values embedded into srvcp.exe at compile time. The reason for highlighting the process itself, instead of concentrating solely on specifics of the program is two-fold. If you are a beginner just starting out on malware analysis and wish to gain a fundamental knowledge to analyze .NET or Java malware, then this course is for you. So jne will jump to a given location if zf flag is not set. At a basic level, malware analysis can be as simple as dropping a file into PEStudio - that gets a massive amount of the information you need for DFIR. As the result of these efforts, the process of reverse engineering the program was time consuming yet fulfilling. Under Windows NT we started SoftICE manually using the "net start ntice" command. July 17, 2021. The sub_40517A routine takes a character from the encrypted line and returns the index indicating the location of this character in the string that is embedded into srvcp.exe at offset 409718. We were able to view these memory contents by executing the "d EAX" command in SoftICE. There are various mashing instructions like MOV, SUB, ADD, etc. We then modified one of the letters in the encrypted string so that the new string became "nhl*pwg". You will learn first-hand from a Malware Developers’ perspective what windows API functions are commonly used in malware and finally understand why you need to trace them when reversing malware. According to Joe Abrams, the EFnet version of the trojan is significantly younger than the one operating on DALnet. The following set of assembly instructions convert our input number to an integer Do you remember we learned in our C programming tutorial that argv holds arguments in string form. This is a collection of Software Diagnostics Services webinar transcripts about pattern-oriented software diagnostics developed by Software Diagnostics Institute. The paper below describes an approach to setting up inexpensive and flexible laboratory environment using virtual workstation software such as VMware, and demonstrates the process of reverse engineering a trojan using a range of system monitoring tools in conjunction with a disassembler and a debugger. Backing up the system can be accomplished by making a copy of the files that are used by VMware to represent the virtual machine. Dennis Yurichev, Reverse Engineering for Beginners, https: . We found no evidence that srvcp.exe is capable of spreading or replicating without help of an external program. Many thanks to Slava Frid, who helped us in stepping through particularly cryptic areas of the program's code, and for making his mind available for our picking. An attempt to resolve irc.mcs.net is consistent with the behavior reported by Filemon, which registered the trojan's requests to read the local hosts file. (Some stack padding alignments etc). When searching the Web for information relating to the srvcp.exe trojan we came across a paper by Joe Abrams, in which he analyzed several code sections from one of the variants of this trojan. De-obfuscation of .NET and Java Code. A CrackMe is a small program designed to test a programmer's reverse engineering skills. Reverse engineering is the process of disassembling a binary and understanding the structure of that program.You can refer to the "Compiling C programs" article to see what happens when we compiling a program. el means we are copying data from ESP. Reverse Engineering and Malware Analysis Students; Programmers who want to know how Malware is created; Students planning on entering Malware Analysis and …
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