Trouble reading PDF file? Solution to reading malformed damaged PDF files

Sometimes PDF files can get scrambled and you are stuck not being able to open a PDF file. Most PDF software cannot open the test file below. Adobe Acrobat Reader issues the pop-up screen could not open because it's not a supported file type or the file has been damaged.

Solution: 

Get XpdfReader PDF software which can open a minor malformed PDF file(s)!

Also, XPDFReader does not implement the Adobe JavaScript engine required for interactive features like calculations, validations, or dynamic field updates, make it safer option.

Note: The #1 way to spread malware are PDF files that contain JavaScript script that executes when the file is opened, see my extensive post on this Locking down Adobe Reader to prevent PDF vulnerabilities, as much as possible for the dangers.


For more information about internal structure of PDFs

1. Basic Structure of PDF documents | Automate PDF (automatizarpdf.com)

2. In-depth exploration of PDF document structure - losLab Software Development

3. Great tool to analyze PDFs - PDF Stream Dumper (sandsprite.com)

Test 1:

In the following sample file, the file starts with malformed PDF file signature 

%P!F- which is incorrect and should be %PDF-, as seen in FRHED editor. 

XpdfReader is the only app I came across that could open this file with this first malformed change.

Test 2: 
 
Then I remove leading angle bracket < where there should be two for <<Lineralired, and it opened! 

Source

The original unadulterated file header is

%PDF-1.5%<bh:e2><bh:e3><bh:cf><bh:d3>10 0 obj\<</Linearized 1/L 105981/O 12/E 101484/N 1/T 105677/H [ 502 173]>>endobj

Opened Malformed File

For more information about internal structure of PDFs

1. Basic Structure of PDF documents | Automate PDF (automatizarpdf.com)

2. In-depth exploration of PDF document structure - losLab Software Development

Example of absolute minimal PDF file contents "Hello World", copy and pasted into FHRED.

%PDF-1.1
1 0 obj
<< /Type /Catalog /Pages 2 0 R >>
endobj
2 0 obj
<< /Type /Pages /Kids [3 0 R] /Count 1 >>
endobj
3 0 obj
<< /Type /Page /Parent 2 0 R /MediaBox [0 0 200 200] /Contents 4 0 R /Resources << /Font << /F1 5 0 R >> >> >>
endobj
4 0 obj
<< /Length 44 >>
stream
BT
/F1 12 Tf
72 100 Td
(Hello World) Tj
ET
endstream
endobj
5 0 obj
<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>
endobj
xref
0 6
0000000000 65535 f 
0000000009 00000 n 
0000000056 00000 n 
0000000107 00000 n 
0000000212 00000 n 
0000000310 00000 n 
trailer
<< /Size 6 /Root 1 0 R >>
startxref
380
%%EOF

Here's Hello World.pdf opened in XpdfReader 4.06