this post was submitted on 25 May 2026
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How would you do this in C? I'm a beginner. Does it entail checking/disallowing certain characters and data types? What? π
How do you sanitize your inputs or how do you exploit inputs which are not sanitized.
Santize inputs.
I'll get back to you on exploits when I can write something that throws zero compilation errors. π
Couple big things are 1. Only accept reasonable characters, on a white list instead of rejecting bad characters based on a black list. This will mean you are less likely to forget to block /0 for example. 2. Understand how strings work and ensure both reading and writing to that string doesn't extend beyond the end of memory allocated for the string. For example do you understand what the /0 would do to a string your program accepts?
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If you use the SQLite C API like this
char query[256];
snprintf(query, sizeof(query),
"SELECT * FROM users WHERE username = '%s'", username);
int rc = sqlite3_exec(db, query, NULL, NULL, &err_msg);
and someone enters `Robert; DROP Table Students;--' as username, it deletes the table Students.
const char *sql = "SELECT * FROM users WHERE username = ?";
int rc = sqlite3_prepare_v2(db, sql, -1, &stmt, NULL);
if (rc != SQLITE_OK) {
fprintf(stderr, "Failed to prepare statement\n");
return;
}
sqlite3_bind_text(stmt, 1, username, -1, SQLITE_STATIC);
Using this "prepared statement" and "bind", your code is secured against such SQL injection attacks.
Many languages like C, Java, Python, etc allow you to construct SQL queries or SQL statements, where SQL is its own language used to communicate with a database, like Oracle or MySql, or Postgres or MSSQL. One way to do this is to construct a string in your language using whatever string functions, concatenation etc available in your language. The problem occurs because usually you want some kind of user input as one of the parameters in your sql query, in order to fetch the correct records the user is asking for. Like say a record ID or name. If you do not properly sanitize that ID or name which originally comes from some type of user input, then a malicious user could carefully craft an ID or name which includes their own SQL and other special characters, which will interfere with the query you intended to construct, and instead do something malicious. Like delete records or obtain records the user is not supposed to have access to.
There are many ways to guard against this, and you should learn about this when you start working with SQL and databases. Itβs called a SQL injection.
There is another type of code injection which can occur if you are making exec() calls (or whatever your language uses) to run shell commands. Similar caution should be taken there.
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You wouldn't - what they're describing is called "SQL injection" - a way to fool poorly written web server code (regardless of what language it's writen in) into executing SQL code. The poorly written server code takes what's entered in a form field on a web page and pastes it into a skeleton of a SQL statement - in this case the text in the input field is SQL that ends the intended statement, followed by a new statement that deletes a table. For this to even work, the SQL skeleton on the server would have to be structured in just the right way so the modified version with the pasted-in text still makes sense. For this reason, hackers attempting SQL injection usually have to do a lot of trial and error to get something to happen. The only way it can work at all is if the server software handling the web page sends SQL commands to a database server as text, as if they're being typed in, and the server executes them. You can't inject C in this way because unlike SQL, C code isn't just executed, C programs have to be precompiled.
My day has come!!!
Don't sanitise inputs. Reject non-conforming inputs entirely.
But otherwise: yes.
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I οΏ½ Unicode!
I like this very much! It implies that the person expressing this knows exactly how they feel about Unicode. It's just us, the readers (or some other link in the chain), who have/ has the wrong encoding.
Allow me to introduce you to my favorite Unicode character, the zero width space
thatβββββββ ββββsoundsβββββββββββββββββββββββββ aweββββsome!ββββββββββββββββββββββββββββββββββββββ (there's 10k zero width spaces between the quotes 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βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ'.)
thats a 29kb comment right there
I'll be damned. The crazy son of a bitch did it!
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Checks out:
On Interstellar it shows up as normal spaces for me so there's just a giant block of empty space
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Unfortunately, evil people blacklist this character a lot :(
May I introduce you to my favorite Unicode character, the Braille zero dots
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Unless they work for Microsoft. Teams has been showing οΏ½ instead of Γ€ for the caller's name in the popup when someone calls for several weeks now. It didn't use to do that before. I don't think they care anymore.
I don't think it's even "they" any more.
ββΔ
Not always, but most times, yeah.
Pretty sure that's illegal here.
Depends on if it breaks the form and they get called. Actually if it gets through they might rightfully question their sanitation coding.
Allow me to make one thing perfectly clear: If you insert those symbols into my perfectly working website... only to mess with me and inadvertently give me vietnam-style flashbacks to the days when I had to deal with incredibly badly formed and misencoded CSV-files on the daily...
Then I will find you and break into your home to replace every second sock with one of the same color and pattern but slightly different make, size or material and you will always wonder why you can't find any exactly fitting pairs of socks anymore.
I willingly embraced mismatched socks years ago. I just pretend it's a fashion statement. Come at me bro.
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To the op of the screenshot meme, calm down satan
Calm down satan π
Former dev here, can confirm on occasion it does.
Usually only happened when a French person copied and pasted their text directly from a Word document... dang weird spaces and accented characters... drove my boss mad when I told him it was because it French, and not a glitch.
Still had to work around it... text counters in textboxes had to account for accented characters, which took two bytes instead of one.
"I only have 2000 letters!" ... 2000 including 200 accent characters made it 2200 characters, not 2000.
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Ok calm down there Satan. Leave some chaos for the rest of us π
my favorite thing to do is go to small town websites and look at the page source for their forms. 70% of the time they have inputs commented out to "disable" forms or just deprecated functionality.
I like to uncomment them and submit the forms just to fuck with them π€£
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I remember feeling extra powerful when Moonshell for the DS shipped with UTF-8 and UTF-16 support because the developer was japenese and wanted to make sure any language would work.
Actual monster
β‘β‘β‘β‘β‘β‘β‘β‘ !!
You monster!
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