diff --git a/Bitdefender%3A-UPX-Unpacking-Featuring-Ten-Memory-Corruptions---Landave%27s-Weblog.md b/Bitdefender%3A-UPX-Unpacking-Featuring-Ten-Memory-Corruptions---Landave%27s-Weblog.md new file mode 100644 index 0000000..1c5c2f5 --- /dev/null +++ b/Bitdefender%3A-UPX-Unpacking-Featuring-Ten-Memory-Corruptions---Landave%27s-Weblog.md @@ -0,0 +1,7 @@ +
This put up breaks the 2-year silence of this weblog, [Memory Wave Experience](https://nativeheaven.com/index.php/Priming_In_Psychology) showcasing a collection of [Memory Wave Experience](http://napzack.sakura.ne.jp/cgietc/epad/epad.cgi) corruption vulnerabilities in Bitdefender’s anti-virus engine. The objective of binary packing is to compress or obfuscate a binary, normally to save space/bandwidth or to evade malware analysis. A packed binary usually accommodates a compressed/obfuscated information payload. When the binary is executed, a loader decompresses this payload after which jumps to the actual entry level of the (interior) binary. Most anti-virus engines assist binary unpacking at the least for packers (equivalent to UPX) that are extremely popular and which might be additionally utilized by non-malware software. This blog publish is about UPX unpacking of PE binaries in the Bitdefender core engine. The next vulnerabilities are presented within the control-flow order of the UPX unpacker. Disclaimer: In the following, decompiled code from Bitdefender’s core engine is presented. The naming of variables, fields, and macros is heavily inspired by the original UPX. For some snippets, a reference to the original function is added for [comparability](https://www.brandsreviews.com/search?keyword=comparability).
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It is probably going that some varieties are incorrect. After the UPX loader has been detected, the Bitdefender engine tries to detect whether or not the loader applies a particular type of deobfuscation to the compressed knowledge payload before extracting it. LEFT. If this deobfuscation is detected, then the engine iterates through the corresponding directions of the loader and parses them with their operands in order to have the ability to deobfuscate the info as nicely. Observe how the sure-check on the index variable i is carried out. 16. Particularly, we are able to enhance i from 15 to 17, after which we will overwrite the stack with fully arbitrary data. The debug break is because of the stack canary which we have overwritten. If we proceed, we see that the return fails because the stack is corrupted. Clearly, this offsets must be checked earlier than writing to it. Both checks test against the sphere dword10.
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The sector dword10, sitting on the calling functions’s stack body, is rarely initialized. This makes the certain check ineffective and introduces a fully attacker-controlled heap buffer overflow. After the extraction, the engine attempts to deobfuscate the extracted information with a static XOR key. The sure examine is totally flawed. It ought to check against the scale of the extracted knowledge buffer. Instead, it checks against a worth that's previously set to the raw data size of the section we extracted the info from. These two sizes have nothing to do with each other. Specifically, one might be a lot smaller than the other, or vice-versa. As the function does not return after the primary deobfuscation run, the memory corruption might be triggered up to 0x300 occasions in a row. This enables us to bypass the limitation that in a single deobfuscation run we at all times XOR [Memory Wave](https://git.7milch.com/tiffany4876171) with the same byte. Overall, we then have XORed with C0 C0 C1 C1 C1 C2 C2 for fully arbitrary C0, C1, and C2.
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We will primarily XOR with such a sample of nearly arbitrary size, and swap the byte at most 0x300 occasions. Evidently, this vulnerability is a helpful exploitation primitive as it enables very powerful memory corruptions: XORing allows us to switch selectively solely sure components of data, leaving different components (for [Memory Wave](https://classifieds.ocala-news.com/author/margerygaga) instance heap metadata or critical objects) untouched. A filter is a simple transformation on binary code (say, x86-64 code) that is utilized before compression, with the objective to make the code extra compressible. After we've got decompressed the info, we need to revert this filtering. Bitdefender helps about 15 different filters. Of the 15 filters, about eight appear to be affected by such a heap buffer overflow. I treated all of them together as one bug (in any case, it's not unlikely that they share code). The next memory corruption occurs in a loop of the perform PeFile::rebuildImports (cf.
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