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[2016-03-19 18:50 UTC] vvvaagn at gmail dot com
Description:
------------
tail -f /var/log/kern.log
Mar 19 18:41:33 TZDG001 kernel: [10476143.454202] php[18389]: segfault at ae6572 ip 0000000000d531b4 sp 00007ffea1567a70 error 7 in php[400000+e80000]
(gdb) r test.php ret/crash13
Starting program: /tmp/php-7.0.4/sapi/cli/php test.php ret/crash13
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Program received signal SIGSEGV, Segmentation fault.
zend_string_init (persistent=0, len=2, str=0x121a64c "->") at /tmp/php-7.0.4/Zend/zend_string.h:157
157 zend_string *ret = zend_string_alloc(len, persistent);
(gdb) i r
rax 0xae6572 11429234
rbx 0x7fffffffa880 140737488332928
rcx 0x64c 1612
rdx 0x2 2
rsi 0x3 3
rdi 0xae658a 11429258
rbp 0x2 0x2
rsp 0x7fffffffa7e0 0x7fffffffa7e0
r8 0xfffffffffffffffb -5
r9 0x1 1
r10 0x3 3
r11 0x1214fc0 18960320
r12 0x1206b7a 18901882
r13 0x4 4
r14 0x121a64c 18982476
r15 0x7fffffffa880 140737488332928
!!! rip 0xd531b4 0xd531b4 <add_assoc_string_ex+116>
eflags 0x10206 [ PF IF RF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
maybe potencial attackers can manipulate rip register and get RCE
Test script:
---------------
cat test.php
-------------------
<?php
$testfile = file_get_contents($argv[1]);
try {
$phar = new Phar($testfile);
$phar['index.php'] = '<?php echo "https://twitter.com/vah_13"; ?>';
$phar['index.phps'] = '<?php echo "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"; ?>';
$phar->setStub('<?php
Phar::webPhar();
__HALT_COMPILER(); ?>');
} catch (Exception $e) {
print $e;
}?>
-------------------
root@TZDG001:/tmp/data2# base64 ret/crash13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cC9QSFBNRC9PdW1hf24vcGhwL1BIUGFEUFBQUFBQUFByYy9tYWluL3BocC9QSFBNRC9SdWxML0Rl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Last updated: Mon Nov 03 03:00:01 2025 UTC |
Looks like the source of the issue is in phar_analyze_path, namely in this code: if (!(realpath = expand_filepath(filename, NULL))) { efree(filename); return FAILURE; } #ifdef PHP_WIN32 phar_unixify_path_separators(realpath, strlen(realpath)); #endif slash = strstr(realpath, filename); if (slash) { slash += ((ext - fname) + ext_len); *slash = '\0'; } The problem there is that if fname and thus filename contain \0's, which in this example they do, realpath of course would not contain those parts and thus slash would point past the end of the realpath buffer. I think the best solution would be to just reject filenames that contain \0 outright.attacking vector without local cli <?php $uploaddir = '/var/www/uploads/'; $uploadfile = $uploaddir . basename($_FILES['userfile']['name']); if (move_uploaded_file($_FILES['userfile']['tmp_name'], $uploadfile)) { $testfile = file_get_contents($uploadfile); try { $phar = new Phar($testfile); $phar['index.php'] = '<?php echo "https://twitter.com/vah_13"; ?>'; $phar['index.phps'] = '<?php echo "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"; ?>'; $phar->setStub('<?php Phar::webPhar(); __HALT_COMPILER(); ?>'); } catch (Exception $e) { print $e; } } ?>