CVE-2017-7601 in LibTIFF
Summary
by MITRE
LibTIFF 4.0.7 has a "shift exponent too large for 64-bit type long" undefined behavior issue, which might allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted image.
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Analysis
by VulDB Data Team • 11/28/2022
The vulnerability identified as CVE-2017-7601 resides within LibTIFF version 4.0.7, a widely used library for handling tagged image file format files. This issue manifests as undefined behavior stemming from a problematic shift operation where the exponent value exceeds the capacity of a 64-bit long integer type. The flaw occurs during the processing of malformed image files that contain crafted data structures designed to exploit this specific condition. The root cause can be traced to CWE-758, which describes the weakness of undefined behavior in software implementations, particularly when dealing with arithmetic operations that exceed type limitations. This undefined behavior creates a scenario where the application's execution becomes unpredictable and potentially unsafe.
The technical implementation of this vulnerability involves a bitwise shift operation that uses an exponent value which, when processed on systems with 64-bit long integers, exceeds the maximum representable value. When the shift operation attempts to use such an excessive exponent, the behavior becomes undefined according to the c standard, leading to potential application crashes or system instability. Attackers can leverage this by crafting specially formatted image files that contain malicious shift exponent values, which when processed by applications using the vulnerable LibTIFF library, trigger the undefined behavior. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1203, where adversaries manipulate application inputs to cause system instability or crashes.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially allow for more sophisticated attacks depending on the execution environment and how the vulnerable applications handle the undefined behavior. Remote attackers can exploit this issue without requiring local access or authentication, making it particularly dangerous in networked environments where image processing applications are exposed to untrusted input. Applications that rely on LibTIFF for image processing, including web servers, image viewers, and document management systems, become vulnerable to this attack vector. The vulnerability's potential for unspecified other impacts suggests that under certain conditions, it might be exploitable for more serious consequences beyond simple application crashes, potentially including information disclosure or privilege escalation scenarios.
Mitigation strategies for CVE-2017-7601 primarily focus on updating to patched versions of LibTIFF, specifically version 4.0.8 or later, which contain fixes for the shift exponent validation issue. System administrators should prioritize patching affected applications and services that utilize the vulnerable library, particularly those handling untrusted image files from external sources. Additionally, implementing input validation measures that sanitize image file headers and content before processing can provide an additional layer of defense. Organizations should also consider deploying network segmentation and access controls to limit exposure of vulnerable systems to untrusted inputs. The fix implemented in the patched versions typically involves adding bounds checking for shift operations and ensuring that exponent values remain within valid ranges for the target data types, thereby preventing the undefined behavior that leads to application instability.