Computer Hacking Forensic Investigator CHFI (CHFI) — Questions 526–600

Event ID 4625 indicates a failed logon attempt. Repeated failures from a remote IP suggest a brute-force password guessing attack.

Option A is correct because the first priority at a live scene is to preserve volatile evidence and establish a chain of custody. Photographing the scene and documenting the system state (e.g., running processes, open network connections, logged-in users) captures critical volatile data before any action is taken. This aligns with the order of volatility (RFC 3227), which mandates capturing memory and system state before altering the system.

Alternate Data Streams (ADS) allow hiding data by attaching additional streams to files. They are not visible in standard directory listings.

The HTTP POST request to a remote URL with encrypted data is a classic network-based indicator because it involves communication over a network protocol (HTTP) to an external server. Cuckoo Sandbox captures this as a network artifact, making it a network-based IoC (Option D). Host-based IoCs focus on file system or registry changes, memory-based on in-RAM artifacts, and hash-based on file fingerprints.

Locard's exchange principle states that every contact leaves a trace. In digital forensics, this means that when an attacker interacts with a compromised system, they inevitably leave behind digital artifacts such as log entries, modified files, registry changes, or network connection records. Option D correctly captures this core concept as applied to digital forensics.

A PCAP file captures raw network packets. HTTP is an application-layer protocol that transmits data (e.g., files, web pages) in cleartext over TCP. By reassembling TCP streams from the captured packets, an analyst can directly extract files transferred via HTTP, as the payload contains the actual file content.

These are standard tools used in digital forensics for specific tasks.

NetFlow analysis examines flow records (e.g., IPFIX, NetFlow) to understand traffic patterns, volumes, and anomalies, using tools like SiLK or nfdump.

Event ID 7045 indicates a service was installed on the system, which attackers often use to maintain persistence.

This is a webshell that executes arbitrary operating system commands via the 'cmd' query parameter. It allows remote command execution on the server.

docker export captures the file system of a stopped container as a tar archive for forensic analysis.

The email claims to be from 'ceo@victim.com' but was received from 'mail.attacker.com', indicating the sender forged the From address. This is email spoofing.

The Received headers are added by each SMTP server; the first Received header (bottommost) contains the IP of the originating server.

The USBSTOR registry key records the serial numbers of USB storage devices that have been connected to the system. Its presence indicates a USB device was attached.

LiME (Linux Memory Extractor) is a loadable kernel module that allows full system memory acquisition from Linux systems. It is the standard tool for Linux memory forensics.

Physical acquisition via JTAG or chip-off provides the most complete data extraction because it captures a bit-for-bit copy of the raw NAND flash memory, including deleted files, unallocated space, and system partitions that are otherwise inaccessible. On iOS 14, Apple's security features (e.g., full-disk encryption, SEP) limit logical and file system methods, but physical techniques bypass the operating system to retrieve the entire storage image, albeit with decryption challenges.

Digital evidence must be authentic and its integrity verifiable to meet the legal standard of admissibility, as established by rules such as the Federal Rules of Evidence (FRE 901) and the Daubert standard. Authentication requires proving that the evidence is what it claims to be, typically through a hash value (e.g., MD5, SHA-1, or SHA-256) computed before and after analysis to ensure no tampering occurred. Without verifiable integrity, the evidence could be challenged as altered, making it inadmissible regardless of how it was collected.

The /proc/[pid]/cmdline file contains the full command line of the process, and /proc/[pid]/environ contains environment variables. The question asks for both, but cmdline is specifically for command line. However, for both, cmdline is primary.

Option B is correct because the `adb shell dd if=/dev/block/mmcblk0 of=/sdcard/physical.img` command uses the `dd` utility to perform a bit-for-bit copy of the raw block device representing the internal flash memory (mmcblk0) to a file on the device's SD card, which can then be pulled via ADB. This method captures a full physical image, including deleted data and unallocated space, which is essential for deep forensic analysis.

GPT uses GUIDs, supports up to 128 partitions, stores a backup partition table at the end, and uses 64-bit LBA. It does not store partitions in the boot code area.

Locard's principle states that every contact leaves a trace; in digital forensics, this translates to digital traces left behind when a system is accessed.

After identifying suspicious queries, the analyst should check the application server logs to see if the results were sent externally.

Persistence mechanisms like Run keys and scheduled tasks are often monitored by security tools. If malware attempts to delete or modify these after execution, it is trying to remove evidence of persistence, which is a form of log wiping or anti-forensics.

The ListObjects operation lists the objects in an S3 bucket; the CloudTrail event name is 'ListObjects'.

The `cipher /w:C:` command overwrites free space on the C: drive with zeros, making deleted file recovery from unallocated space much more difficult.

Inodes are data structures in ext2/3/4 that store metadata about files and directories.

The presence of '../' sequences in the URI path indicates a path traversal attack attempting to access files outside the web root.

The URI contains '../../../../etc/passwd', which is a path traversal attempt to read the /etc/passwd file. The 404 status indicates the file was not found, but the intent is clear.

The grep command can filter lines containing 'Failed password for root' from the auth.log file. The -i flag is unnecessary as the log is case-sensitive but not needed here.

RAID 5 can tolerate one disk failure. If the replacement disk is smaller than the original, the rebuild may fail or cause corruption.

USB forensics involves registry keys, device logs, and correlation with event logs.

A SYN followed by SYN‑ACK and then RST is typical of a port scan where the scanner sends a SYN, receives a SYN‑ACK (port open), and then immediately resets the connection to avoid completing the handshake.

Timestomping is the deliberate alteration of file timestamps (creation, modification, access) to mislead forensic investigators. In this scenario, the ransomware modified critical system file timestamps to match legitimate Windows files, which is the hallmark of timestomping. This technique is commonly used to evade timeline analysis and hide the true sequence of malicious activity.

SPF pass indicates the sending IP is authorized; DKIM signature validates the email was signed by the domain. Combined, the email is likely not spoofed.

IIS W3C Extended Log Format includes fields: date, time, client IP, cs-uri-stem, sc-status. In the given entry, the status code 200 appears after the URI and before the 0 (sc-substatus).

ADB backup (option C) is the most appropriate logical acquisition method for a locked Android phone because it uses the Android Backup protocol over ADB, which can extract application data without needing to bypass the lock screen, provided USB debugging is enabled and the device authorizes the backup. This method does not require root access or physical disassembly, making it a non-invasive logical acquisition technique.

Cloud Audit Logs in GCP record administrative activities (Admin Activity logs) and data access (Data Access logs) for GCP resources.

In ext4, when a file is deleted, its inode is marked as free, and data blocks are added to the free block bitmap. Recovery is possible if the blocks have not been reused.

Physical acquisition is the most comprehensive method because it creates a bit-for-bit copy of the entire flash storage, including the operating system, kernel, unallocated space, and deleted file remnants. Even with the passcode known, a locked iPhone restricts file system access via USB, but physical acquisition (often using advanced techniques like JTAG or chip-off) bypasses these restrictions to extract the raw NAND data, yielding the fullest forensic picture.

Circumstantial evidence is a recognized type of evidence under the rules of evidence because it relies on an inference to connect a fact to a conclusion, rather than directly proving the fact. In digital forensics, circumstantial evidence might include log entries showing a user logged in at the time of an incident, which indirectly suggests involvement. It is admissible as long as the chain of inferences is reasonable and supported by other facts.

In FAT32 file systems, the File Allocation Table (FAT) uses 32-bit entries to track cluster allocation. The value 0x0FFFFFFF is the defined end-of-file (EOF) marker, indicating that the current cluster is the last in a file's cluster chain. This is a standard FAT32 convention, distinct from other special values like free or bad clusters.

In ext3, deleting a file clears the inode and data block pointers. Recovery requires scanning the raw disk for file signatures (file carving) because the inode no longer points to the data.

Option A is correct because documenting the SIM card information, such as the ICCID (Integrated Circuit Card Identifier) and IMSI (International Mobile Subscriber Identity), is a critical step in establishing chain of custody and preserving evidence that may link the device to a specific subscriber or network. This documentation must occur before any acquisition to ensure the SIM's data is not altered by subsequent imaging or isolation procedures.

Plaso (log2timeline) and The Sleuth Kit (with mactime) are both used to create super timelines from file system metadata.

Registry Run keys, scheduled tasks, and service installations are common persistence mechanisms. Prefetch files and LNK files are forensic artifacts but not persistence mechanisms.

A file that accepts commands via HTTP and executes them on the server is a web shell. ASPX is a common extension for .NET web shells.

Option C is correct because imaging each physical drive individually with a write blocker preserves the exact bit-for-bit state of every disk in the RAID array, including metadata, parity, and superblock information. This approach ensures that the logical volume can be reconstructed later in a controlled environment without altering the original evidence, which is critical for maintaining chain of custody and forensic integrity.

After a factory reset on an Android device, the operating system typically performs a 'fastboot format' or 'wipe data/factory reset' which only unmounts the userdata partition and marks its blocks as free in the ext4 or F2FS filesystem metadata. The actual user data (photos, contacts, etc.) remains physically stored in the NAND flash memory until those blocks are overwritten by new data. Because no overwrite has occurred in this scenario, the raw data is still recoverable using forensic tools that bypass the filesystem and read the flash memory directly.

The pattern 1' OR '1'='1 is a classic SQL injection payload attempting to bypass authentication or extract data. The single quote and OR condition are characteristic of SQLi.

The 'docker logs' command captures container stdout/stderr, and the 'docker cp' command can copy log files from the container filesystem. Other methods are not directly applicable.

Mobile forensics requires enabling debugging, selecting extraction method, and parsing data.

Option C is correct because volatile data, such as the contents of RAM, is lost when power is removed. The first responder must capture this data using a forensic tool (e.g., FTK Imager, WinPmem, or LiME) before performing a shutdown. This follows the Order of Volatility (RFC 3227), which prioritizes capturing registers, cache, and RAM before any persistent storage.

The unified logging system in macOS stores log data in /private/var/db/diagnostics/ in a binary format, while /var/log/system.log is a legacy plain-text log. The diagnostics directory contains more detailed logs for forensic analysis.

Multi-tenancy in cloud environments means that evidence from one tenant may be co-mingled with data from other tenants, and isolation can be difficult.

Worm propagation often scans many internal hosts on SMB port 445 (indicating lateral movement) and uses consistent payload sizes. A single SYN to an external IP on port 445 could be a normal file share connection. Internal scanning and similar packet sizes are indicative of automated worm behavior.

The correct filter for HTTP traffic in Wireshark is 'http'. Wireshark uses protocol names in lowercase for display filters.

The lowest (last) 'Received' header in the email is the first hop from the sender's MTA, making it the most trustworthy for the originating IP.

The presence of 'UPX0' as the entry point section name and an entropy value of 7.8 (very high, indicating compression or encryption) strongly suggests the malware is packed with UPX (Ultimate Packer for eXecutables). The correct next step is to use UPX with the -d (decompress) switch to unpack the binary, restoring the original executable for static analysis. This is a standard, reversible unpacking method that does not require dynamic analysis or disassembly of the packed stub.

A web shell is a script uploaded to a web server that allows remote command execution. The filename and behavior match a webshell.

The `conv=noerror,sync` option in `dd` instructs the tool to continue processing even when a read error is encountered (`noerror`) and to pad the output block with zeros (`sync`) to maintain the correct block size and offset alignment. This ensures that the forensic image remains a bit-for-bit copy of the source device in terms of size and structure, with corrupted sectors replaced by zeros rather than causing the imaging process to abort or produce a truncated image.

Option C is correct because the Fourth Amendment requires law enforcement to obtain a warrant based on probable cause, obtain the owner's consent, or demonstrate exigent circumstances before seizing a computer for forensic examination. This protects against unreasonable searches and seizures, and a computer's storage capacity means it can contain vast amounts of personal data, so the same constitutional protections apply as to a physical home or vehicle.

PEiD (Portable Executable Identifier) is a static analysis tool that can parse the PE file structure, including the Import Address Table (IAT), to reveal which DLLs and functions are imported. Since the question specifies static analysis and viewing the IAT, PEiD is the best choice because it directly reads the PE headers without executing the file.

MRU lists are stored in the registry under NTUSER.DAT\(various keys such as \Software\Microsoft\Windows\CurrentVersion\Explorer\ComDlg32\OpenSavePIDlMRU). They track recently opened files.

The first responder should photograph the scene and all visible evidence before any actions that might alter the state. This preserves a visual record of the original condition.

Option A is correct because RAM contains volatile data that is lost when power is removed. FTK Imager or dd can capture the exact contents of memory, preserving running processes, open network connections, encryption keys, and other transient evidence critical to the investigation.

Wireshark is the best tool for capturing and analyzing network traffic because it can intercept packets at the network interface level, allowing you to inspect the full payload and headers of outbound connections from `svchost.exe` to the malicious IP. This enables deep analysis of protocols, data exfiltration attempts, and command-and-control communication patterns, which is essential in malware forensics.

Volatile data such as RAM contents, network connections, and running processes are lost when the system is powered off. Non-volatile data on the hard drive remains.

GrayKey is a specialized forensic tool developed by GrayShift that performs physical extraction on iOS devices, including bypassing passcodes and obtaining full file system images. It exploits hardware and software vulnerabilities in iOS to extract data, making it the correct choice for this specific task.

TRIM allows the SSD to erase data blocks immediately after deletion, making it impossible to recover data from those blocks using traditional file carving or undelete methods.

Alternate Data Streams (ADS) allow data to be attached to a file as a separate stream, invisible in standard directory listings.

Option B is correct because running a trusted version of win32dd.exe (now commonly part of the Belkasoft or DumpIt suite) from a write-protected USB drive ensures the tool binary is not modified by the compromised system and does not write any artifacts to the server's disk. Capturing memory directly to the USB drive minimizes the forensic footprint by avoiding writes to the server's local storage, preserving the integrity of the evidence.

The hash 'd41d8cd98f00b204e9800998ecf8427e' is the MD5 hash of an empty file (zero bytes). In malware forensics, a file hash is a classic file-based indicator of compromise (IoC) used to uniquely identify known malicious files. Option D is correct because this hash directly identifies a specific file, making it a file hash indicator.

A hardware write blocker is a device placed between the suspect drive and the forensic workstation that intercepts and blocks any write commands from the host operating system, ensuring that the original evidence drive remains unaltered. This is critical for maintaining the integrity of digital evidence, as any modification to the source drive could render it inadmissible in court. The primary purpose is therefore to prevent any writes to the original evidence drive, preserving its exact state for forensic analysis.

Packing is an anti-forensic technique that compresses or encrypts the malware's executable code, making static analysis difficult by obfuscating the original binary signature and strings. This allows malware to evade signature-based detection by antivirus and forensic tools until the packed code is unpacked at runtime.