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PHP 7.1.0/5.6.29 missing null byte checks for paths in ZipArchive::extractTo

Posted on 30 November -0001

<HTML><HEAD><TITLE>PHP 7.1.0/5.6.29 missing null byte checks for paths in ZipArchive::extractTo</TITLE><META http-equiv="Content-Type" content="text/html; charset=utf-8"></HEAD><BODY>Description:
------------
ZipArchive->extractTo() doesn't ensure that pathnames lack NULL byte, which might allow attacker to manipulate the directory path.

Affected method:
------------------------------------------
static ZIPARCHIVE_METHOD(extractTo)
{
    struct zip *intern;
 
    zval *self = getThis();
    zval *zval_files = NULL;
    zval *zval_file = NULL;
    php_stream_statbuf ssb
;..
    if (!self) {
        RETURN_FALSE;
    }
 
    if (zend_parse_parameters(ZEND_NUM_ARGS(), "s|z", &pathto, &pathto_len, &zval_files) == FAILURE) {
        return;
    }
 
    if (pathto_len < 1) {
        RETURN_FALSE;
    }
------------------------------------------




Test script:
---------------
<?php

if(file_exists("LEVELA/EXTRACTED__HERE")) echo "LEVELA/EXTRACTED__HERE EXISTS!!!1
";
if(file_exists("LEVELA/LEVELB/EXTRACTED__HERE")) echo "LEVELB/EXTRACTED__HERE EXISTS!!!2
";

$zip = new ZipArchive;
if ($zip->open('toPack/EXTRACTED__HERE.zip') === TRUE) {
   $zip->extractTo("./LEVELA/LEVELB");
   $zip->close();
   echo "ok
";
} else {
   echo "failed
";
}

if(file_exists("LEVELA/EXTRACTED__HERE")) echo "LEVELA/EXTRACTED__HERE EXISTS!!!3
";
if(file_exists("LEVELA/LEVELB/EXTRACTED__HERE")) echo "LEVELB/EXTRACTED__HERE EXISTS!!!4
";

?>

Expected result:
----------------
expected parameter not string

Actual result:
--------------
# php zip.php 
ok
LEVELA/EXTRACTED__HERE EXISTS!!!3



Credit: Maksymilian from CXSECURITY.COM
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