CVE-2017-13755 in The Sleuth Kit
Summary
by MITRE
In The Sleuth Kit (TSK) 4.4.2, opening a crafted ISO 9660 image triggers an out-of-bounds read in iso9660_proc_dir() in tsk/fs/iso9660_dent.c in libtskfs.a, as demonstrated by fls.
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Analysis
by VulDB Data Team • 12/27/2022
The vulnerability identified as CVE-2017-13755 represents a critical out-of-bounds read flaw within The Sleuth Kit (TSK) version 4.4.2, specifically affecting the iso9660_proc_dir() function located in tsk/fs/iso9660_dent.c within the libtskfs.a library. This issue manifests when processing crafted ISO 9660 image files through the fls utility, which is commonly employed in digital forensics for file system analysis. The flaw arises from insufficient input validation and boundary checking during the parsing of ISO 9660 directory structures, creating a scenario where maliciously constructed ISO files can trigger memory access violations.
The technical implementation of this vulnerability stems from improper handling of directory entry parsing within the ISO 9660 file system parser. When the iso9660_proc_dir() function processes directory structures, it fails to adequately validate the bounds of directory entry data, allowing an attacker to craft ISO files that contain malformed directory entries. This weakness enables an out-of-bounds memory read operation that can potentially expose sensitive data from adjacent memory locations or cause application crashes. The vulnerability directly maps to CWE-125, which describes out-of-bounds read conditions in software implementations, and represents a classic example of buffer over-read vulnerabilities that can lead to information disclosure or denial of service scenarios.
From an operational perspective, this vulnerability poses significant risks to digital forensics workflows that rely on TSK for evidence analysis. Security professionals and forensic investigators using fls or other TSK-based tools for ISO image analysis could inadvertently trigger the vulnerability when processing compromised or maliciously crafted ISO files. The impact extends beyond simple crashes, as the out-of-bounds read could potentially expose confidential information stored in adjacent memory regions, making this a serious concern for forensic analysts handling sensitive evidence. This vulnerability particularly affects systems where automated processing of ISO images occurs, as the flaw can be exploited without user interaction, potentially allowing remote code execution or information disclosure attacks.
Mitigation strategies for CVE-2017-13755 should prioritize immediate patching of The Sleuth Kit to version 4.4.3 or later, which contains the necessary fixes for the iso9660 directory parsing logic. Organizations should implement strict input validation protocols for all ISO image processing activities, including the use of sandboxed environments when analyzing untrusted ISO files. Additionally, system administrators should consider implementing network segmentation and access controls to limit exposure to potentially malicious ISO files. The vulnerability's exploitation aligns with ATT&CK technique T1059.007, which involves the use of scripting languages, and represents a potential entry point for attackers seeking to compromise forensic analysis systems. Regular security assessments and vulnerability scanning should include verification of TSK versions to ensure compliance with security patches, particularly in environments handling sensitive digital evidence where the integrity of forensic tools is paramount.