CHFI Practice Test 4 — 10 Questions

Question 1

An incident responder analyzes a compromised system and finds evidence of timestomping: the Modified timestamp of a malicious DLL is earlier than the Creation timestamp. Additionally, the DLL is encrypted with an XOR key. Which anti-forensic techniques are being employed?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Timestomping and obfuscation. Timestomping is confirmed because the Modified timestamp (which tracks file content changes) is earlier than the Creation timestamp, which is logically impossible under normal file system operations—this indicates an attacker deliberately set the Modified timestamp backward to evade timeline analysis. The XOR encryption of the DLL is a form of obfuscation, a technique used to hide the true content of the file from static analysis tools and signature-based detection. Together, these two actions represent the anti-forensic techniques of timestomping and obfuscation.

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Packer and anti-debugging

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Rootkit installation and process hiding

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Log wiping and data hiding

Question 2

An email forensic analyst receives a suspicious email and wants to trace its origin. Which email header field provides the most reliable information about the IP address of the sending SMTP server?

Accepted Answer

Received. The 'Received' header is the most reliable source for tracing the origin of an email because each SMTP server that handles the message adds a new 'Received' header at the top, recording the IP address of the sending server (from the HELO/EHLO handshake) and the receiving server. The bottommost 'Received' header typically contains the IP address of the original sending SMTP server, as it is added by the first receiving MTA. This field is standardized in RFC 5321 and is the primary forensic artifact for email source identification.

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Return-Path

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DKIM-Signature

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X-Originating-IP

Question 3

During a forensic investigation, the analyst needs to verify the integrity of a forensic image. The analyst originally computed MD5 and SHA-1 hashes of the source drive. Which action BEST ensures the image has not been altered?

Accepted Answer

Recompute MD5 and SHA-1 hashes of the image and compare with the original. Recomputing the MD5 and SHA-1 hashes of the forensic image and comparing them to the original values is the definitive method to verify integrity. Hash functions produce a fixed-size digest that changes completely if even a single bit of the image is altered, providing cryptographic assurance that the image is an exact bit-for-bit copy of the source drive. This process directly validates data integrity, which is a core requirement in forensic acquisition.

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Check that the image was created using a write blocker

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Compare the file size of the image with the original drive's capacity

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Open the image in FTK Imager and browse a few files

Question 4

You are imaging a suspect's hard drive using a write blocker and dd command. After imaging, you verify the hash of the original drive and the image file. The original drive hash is SHA1: A1B2C3D4E5..., and the image hash is SHA1: F6G7H8I9J0... What is the most likely cause of the mismatch?

Accepted Answer

The write blocker malfunctioned and allowed writes to the original drive. The hash mismatch indicates that the data on the original drive and the image file are not identical. A write blocker malfunction that allowed writes to the original drive during the imaging process would alter the source data after the initial hash was computed, causing the final hash of the original drive to differ from the hash of the image file taken at a different point in time. This is the most direct cause of a hash mismatch because the write blocker's primary purpose is to prevent any modification to the evidence.

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The dd command used a different block size

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The dd command compressed the output

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The image file was corrupted during transfer

Question 5

During a forensic investigation of a hard disk, the investigator finds that the partition table is missing. The disk was previously partitioned using GPT. Which area of the disk should be examined to recover the GPT partition table?

Accepted Answer

LBA 1 (sector 1). In GPT (GUID Partition Table) disks, the primary partition table is stored in LBA 1 (sector 1), immediately following the protective MBR at LBA 0. When the partition table is missing, examining LBA 1 allows recovery of the GPT header, which contains pointers to the partition entry array. This is the correct location because GPT uses LBA 1 for its header, not the last sector or the MBR.

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Last sector of the disk

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Volume boot record

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Master Boot Record (LBA 0)

Question 6

A forensic analyst receives a mobile device that has been factory reset. Which of the following types of data is MOST likely to be recoverable using advanced forensic techniques?

Accepted Answer

Google account tokens and cached credentials. A factory reset typically does not overwrite the flash memory where Google account tokens and cached credentials are stored. Advanced forensic techniques, such as chip-off or JTAG, can recover these remnants from the NAND flash memory, as the reset only marks the storage blocks as available for reuse without physically erasing the data.

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Deleted text messages and call logs, but not app data

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All user data, as factory reset only deletes file pointers

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No data is recoverable after a factory reset on modern devices

Question 7

During a mobile forensics investigation, an examiner needs to acquire data from an iPhone running iOS 14. Which of the following acquisition methods provides the MOST complete data extraction?

Accepted Answer

Physical acquisition via JTAG or chip-off. 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.

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File system acquisition via jailbreak

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Manual acquisition by browsing the device

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Logical acquisition via iTunes backup

Question 8

In network forensics, an analyst captures traffic and sees a large number of ICMP echo requests from 10.0.0.1 to 10.0.0.2 with varying payload sizes. What is the most likely scenario?

Accepted Answer

A DoS attack using ICMP floods. The scenario describes a single source sending a large number of ICMP echo requests to a single destination with varying payload sizes. This is characteristic of an ICMP flood attack, a type of DoS attack where the attacker overwhelms the target with echo requests, consuming bandwidth and processing resources. The varying payload sizes may be an attempt to evade simple packet filters or to maximize resource consumption. In contrast, a ping sweep would involve sending requests to multiple destinations to discover live hosts, not a sustained high-volume stream to one host. Therefore, this is most likely a DoS attack, not reconnaissance.

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Network reconnaissance (ping sweep)

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A man-in-the-middle attack

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A DNS amplification attack

Question 9

An analyst discovers a hidden partition on a hard drive that does not appear in the standard MBR partition table. The drive uses GPT partitioning. Which area of the disk should be examined to find evidence of a hidden partition?

Accepted Answer

The GPT header and partition entry array located after the protective MBR. In GPT partitioning, the protective MBR in sector 0 only contains a single partition entry of type 0xEE to prevent legacy tools from misinterpreting the disk. The actual partition information, including any hidden partitions, is stored in the GPT header (typically in sector 1) and the partition entry array that follows. Therefore, examining the GPT header and partition entry array is necessary to detect partitions not visible in the MBR.

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The Master Boot Record (MBR) in sector 0

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The Volume Boot Record (VBR) of the C: drive

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The Host Protected Area (HPA) at the end of the disk

Question 10

During a forensic examination of a Windows system, an analyst finds a file that appears to be zero bytes in size when viewed in Windows Explorer, but the file's properties show a size on disk of 4 KB. What is the most likely explanation?

Accepted Answer

The file is stored in an alternate data stream (ADS). An alternate data stream (ADS) allows additional data to be stored with a file in NTFS. Windows Explorer typically displays only the size of the main file stream, not the ADS. Therefore, a file with a zero-byte main stream but an ADS containing data will show a logical size of 0 bytes, while the 'size on disk' reflects the allocated clusters for the ADS data (e.g., 4 KB). This is a common technique used to hide data.

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The file contains only slack space

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The file is compressed using NTFS compression

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The file is a sparse file