EnCase Forensic Imager 7.10 Denial Of Service / Heap Buffer Overflow

2016.11.29
Risk: High
Local: Yes
Remote: No
CVE: N/A
CWE: CWE-119

SEC Consult Vulnerability Lab Security Advisory < 20161128-0 > ======================================================================= title: Denial of service & heap-based buffer overflow product: Guidance Software EnCase Forensic Imager & EnCase Forensic vulnerable version: EnCase Forensic Imager<= 7.10 EnCase Forensic (tested with version 7.08.00.137) fixed version: - CVE number: - impact: high homepage: https://www.guidancesoftware.com/encase-forensic-imager found: 2016-09-30 by: Wolfgang Ettlinger (Office Vienna) SEC Consult Vulnerability Lab An integrated part of SEC Consult Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich https://www.sec-consult.com ======================================================================= Vendor description: ------------------- "When time is short and you need to acquire entire volumes or selected individual folders, EnCase Forensic Imager is your tool of choice. Based on trusted, industry-standard EnCase Forensic technology, EnCase Forensic Imager: * Is free to download and use * Requires no installation * Is a standalone product that does not require an EnCase Forensic license * Enables acquisition of local drives (network drives are not able to be acquired with Imager) * Provides easy viewing and browsing of potential evidence files, including folder structures and file metadata * Can be deployed via USB stick and used to perform acquisition of a live device" URL: https://www.guidancesoftware.com/encase-forensic-imager Business recommendation: ------------------------ SEC Consult recommends not to use Encase Forensic Imager or the Encase Forensic Suite until a thorough security review has been performed by security professionals and all identified issues have been resolved. Vulnerability overview/description: ----------------------------------- 1) Denial of Service Several manipulated hard disk images cause Encase Forensic Imager to crash. A suspect manipulating the hard drive could potentially hinder an investigator from using Encase Forensic Imager for creating hard disk images. Encase Forensic (v7) has been tested and found to be affected as well. 2) Heap-based buffer overflow Using a manipulated ReiserFS image an attacker can overwrite heap memory on the investigator's machine. Because of several restrictions SEC Consult was unable to create an exploit that works reliably within a reasonable timeframe. However, as with most heap-based buffer overflow vulnerabilities it is possible that an attacker could gain arbitrary code execution nevertheless. Proof of concept: ----------------- SEC Consult has created proof of concept disk images that will crash Encase. Those PoC images will not be released. 1) Denial of Service The following list demonstrates cases that cause Encase to crash. The investigators would be unable to analyze the hard disk/partition/image using the affected products: * Ext3: - Several conditions cause Encase Forensic Imager to encounter an div/0 exception. Disk images that were manipulated in the following way demonstrate this issue. Those crashes have not been further investigated as to whether code execution is possible. + nummer of blocks per group: 0xFFFFFFFF + total numer of blocks: 0xFFFFFFFF + last mount path: 'A'*100000 + volume name: 'A'*100000 + block number of the superblock: 0 + FS-Id: 'A'*100000 - Manipulating the size of the inode structure value (e.g. 0xFFFF) causes Encase Forensic Imager to write beyond the limits of a previously allocated (VirtualAlloc) segment. * Iso9660: - If the length of a file name is specified in a way that it would exceed the end of the last block, Encase Forensic Imager crashes while trying to read beyond an allocated segment. * ReiserFs: - When setting a block size of below 0x200 the application overwrites heap memory with attacker-supplied data. * GPT: - When specifying an overly long name (in our setup longer than 0x3fc6) for a partition, Encase Forensic crashes failing to read memory when trying to determine the length of the string. The partition table can be constructed in a way that it can also be used for storing data. However, an investigator using Encase will not be able to analyze it. 2) Heap-based buffer overflow The manipulated ReiserFs image that causes the application to overwrite heap memory can be tuned to overwrite heap-data with attacker-controlled data. The application calculates a value (here called "dev_block_count") as: dev_block_count = blocksize from image (e.g. 0x200) / blocksize of reading device (typically 0x200) * number of blocks .text:006F5306 mov ecx, [esi+14Ch] ; ecx = blocksize (device, 0x200) .text:006F530C movzx eax, [esp+90h+var_54] ; eax = blocksize (img) .text:006F5311 xor edx, edx .text:006F5313 div ecx ; div eax / ecx .text:006F5315 push 0 .text:006F5317 mov edx, eax .text:006F5319 imul edx, [esp+94h+var_80] ; * numblocks If this value is zero (which is the case when the blocksize from the image is smaller than 0x200), later in the program it is corrected to the value 1 (@0064B7AA). This causes the application to later allocate 4 bytes of memory (the corrected value of 1 * 4, @006F5426). Then the first block of the image is copied to the allocated 4-byte heap space. The length to be copied is calculated based on the number of blocks specified in the image (maximum 0x200). Vulnerable / tested versions: ----------------------------- At least version 7.10 of Encase Forensic Imager has been found to be vulnerable. This version was the latest at the time the security vulnerabilities were discovered. The disk images that caused crashes for Encase Forensic Imager also caused crashes with Encase Forensic version 7.08.00.137. It is unknown whether Encase Forensic v8 is affected as well. Vendor contact timeline: ------------------------ 2016-10-07: Contacting vendor (sales team) through email, requesting security contact, sending responsible disclosure policy & encryption keys 2016-10-14: No answer, extending email recipient list, requesting security contact again 2016-10-14: Vendor: our request has been sent to management team, they will follow up 2016-10-17: Vendor: one of their security representatives will be reaching out shortly. 2016-10-28: Asking again for security contact, kind reminder of latest release date per 2016-11-26 2016-10-28: Vendor: Verified that request has been passed on to proper department, they will follow up on this 2016-11-07: Asking again for security contact, reminding them again that release date is in about three weeks 2016-11-08: Extending email recipient list again, including SVP Product Engineering explaining unsuccessful attempts to receive a security contact 2016-11-14: Still no answer, reminding Guidance Software again about the release date which has been set to 2016-11-28 now. Told them that the initial vulnerabilities also affect Encase Forensic and not only Encase Forensic Imager. 2016-11-14: Vendor: "send the alleged vulnerability to us for review" (signed email) 2016-11-14: Sending the advisory encrypted to the vendor, including proof of concept disk images to reproduce the issues 2016-11-14: Vendor: "We will look at the issues and will address them in future release(s) if necessary" 2016-11-15: Asking if there is a hotfix planned, offering to delay the advisory release for a few days if necessary, otherwise we'll keep the set release date 2016-11-15: Vendor: they will fix the issue later and are fine patching it after advisory release 2016-11-25: Asking if any fixes are available 2016-11-28: Releasing security advisory Solution: --------- The vendor told SEC Consult they investigate the issues and will fix them at a later date. Workaround: ----------- None Advisory URL: ------------- https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SEC Consult Vulnerability Lab SEC Consult Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich About SEC Consult Vulnerability Lab The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. It ensures the continued knowledge gain of SEC Consult in the field of network and application security to stay ahead of the attacker. The SEC Consult Vulnerability Lab supports high-quality penetration testing and the evaluation of new offensive and defensive technologies for our customers. Hence our customers obtain the most current information about vulnerabilities and valid recommendation about the risk profile of new technologies. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Interested to work with the experts of SEC Consult? Send us your application https://www.sec-consult.com/en/Career.htm Interested in improving your cyber security with the experts of SEC Consult? Contact our local offices https://www.sec-consult.com/en/About/Contact.htm ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mail: research at sec-consult dot com Web: https://www.sec-consult.com Blog: http://blog.sec-consult.com Twitter: https://twitter.com/sec_consult EOF W. Ettlinger / @2016


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