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Alibaba OSS Buckets Compromised to Distribute Malicious Shell Scripts by way of Steganography
Cloud
On this weblog entry, we focus on a malicious marketing campaign that targets Alibaba Cloud’s OSS buckets with leaked credentials for malware distribution and cryptojacking.
By: Alfredo Oliveira, David Fiser
July 21, 2022
Learn time: ( phrases)
Beforehand, we reported on how menace actors are focusing on a number of cloud environments comparable to Huawei Cloud to host cryptocurrency-mining malware by abusing misconfiguration points and weak or stolen credentials obtained from a earlier malware an infection.
This time, we now have recognized a malicious marketing campaign utilizing the article storage service (OSS) of Alibaba Cloud (also called Aliyun) for malware distribution and illicit cryptocurrency-mining actions. OSS is a service that permits Alibaba Cloud clients to retailer information like net utility photos and backup data within the cloud. Sadly, this isn’t the primary time that we’ve seen malicious actors focusing on Alibaba Cloud: Earlier this yr, we detailed how malicious actors disabled options inside Alibaba Cloud for cryptojacking functions.
How malicious actors abuse unsecure OSS buckets, credentials
To safe an OSS bucket, a consumer has to arrange a correct entry coverage. If that is accomplished incorrectly, a malicious consumer can add or obtain a consumer’s recordsdata to or from the bucket itself.
Malicious actors may also pay money for a consumer’s OSS bucket by acquiring their AccessKey ID and AccessKey secret or an auth-token. Any of those could be stolen from beforehand compromised providers, notably people who have secrets and techniques accessible as configurations inside plain-text recordsdata or environmental variables. Malicious actors may also get hold of entry to an OSS bucket by utilizing credential stealers. TeamTNT’s prolonged credential harvester is a infamous instance of a stealer that focused a number of cloud environments.
Once we investigated the technical particulars of this marketing campaign, we noticed that one of many shell scripts contained a reference to OSS KeySecret and GitHub. Initially, we assumed that malicious actors merely seek for credentials which were inadvertently pushed into the GitHub public repository.
Determine 1. A remark inside a malicious script suggesting {that a} dangerous developer follow has been exploited
We noticed a touch upon a malicious script in one of many samples that we analyzed and confirmed our preliminary assumption after utilizing Google Translate to acquire an English translation of the remark that was initially written in Chinese language.
Determine 2. The English translation of the remark written inside a malicious script
The function of steganography in distributing malware to exploited OSS buckets
Upon additional investigation, we found that malicious actors uploaded photos that contained an embedded shell script to the compromised OSS buckets utilizing steganography.
Steganography is a way utilized by malicious actors to bypass protection mechanisms, particularly network-related ones. The only model of this tactic entails merely altering the extension of the malicious file to a trivial one, comparable to “.png”. Because of this, a safety proxy that solely seems at a file’s extension would grant entry to the malicious file.
After this method was uncovered, cybercriminals have been pressured to enhance their ways. For instance, they began hiding malware in photos and movies for obfuscation functions. Usually, a easy safety answer seems at a picture file by analyzing its header. If the header matches that of a file sort normally thought-about innocent (like a PNG file), then the answer would grant the file entry into an organization’s community — even when it accommodates malicious scripts.
Within the marketing campaign we analyzed, the malicious actors opted to make use of a easy steganography tactic and embedded malware inside a picture file. The PNG picture itself is a official picture file, however the malicious actors appended a malicious shell script on the finish of it. A consumer would subsequently be capable to entry the picture itself with out seeing the malicious script hooked up to the file.
Determine 3. The picture containing a malicious shell script
As Determine 4 reveals, when the command “file” is used, it reads the header of the image and determines that it’s a picture file. Utilizing a instrument like “hd” to examine the uncooked content material of the file ends in the identical consequence wherein the header is taken into account appropriate with that of a PNG file.
Determine 4. The PNG header of the downloaded file
Nevertheless, upon downloading the picture and doing a better investigation, we discovered the embedded malicious shell script.
Determine 5. The malicious shell script embedded inside a PNG file
The malware authors used a Unix dd command-line utility program to extract the malicious shell script after the obtain was accomplished. As a result of this command is usually utilized in extra superior duties, it’s evident that the authors have no less than intermediate information of Unix techniques.
Determine 6. From PNG file to malicious code execution
Shell scripts goal misconfigured Redis situations to mine Monero
We noticed that the payload itself illicitly mined Monero utilizing XMRig, an open-source and multiplatform Monero miner. The marketing campaign used the xmr-asia1[.]nanopool[.]org pool. The malicious shell scripts additionally focused misconfigured Redis situations, which could be abused to carry out distant code execution (RCE). That is much like what a number of menace actors concerned in a cryptojacking competitors (comparable to TeamTNT and Kinsing) have accomplished up to now.
Conclusion and Pattern Micro answer
We’re constantly observing how cybercriminals are adapting to new environments and focusing on an rising variety of cloud providers. As we predict that this can be a permanent development, we advise cloud customers to remember that normally, malicious actors will proceed to take advantage of each misconfiguration points and design points in cloud providers to simply entry authentication tokens.
Builders also needs to keep away from placing any credentials and secrets and techniques into the versioning techniques of their favors or pushing them into publicly accessible repositories. Certainly, this investigation is additional proof that malicious actors are all the time actively searching for leaked or uncovered credentials.
Safety options comparable to Pattern Micro Cloud One™ shield cloud-native techniques and their numerous layers. By leveraging this answer, enterprises acquire entry to safety for steady integration and steady supply (CI/CD) pipeline and purposes. The Pattern Micro Cloud One platform additionally consists of Workload Safety runtime safety for workloads.
Indicators of compromise (IOCs)
495605cee98f3b437c3744c24fcf255d1cee7717f7e3150d38f95673ca0617e4
8ec8e800fe3f627ce9f49268e4d67e944848f8ae3a8efc2ef6f77e46781a70f3
8bb70f52377091ccbb13e7be0a1d4dab079edeca6adc18b126bbdc40dbcf3ae4
ce95789643e31a65ee77a31c69a6952e9e260200b50e0e8ba6bf8493cce7fb71
34c78249ab1415afacd16cf76375a800d8d56fa5ac60b5522146e65c1521955b
MITRE ATT&CK® desk
Tags
sXpIBdPeKzI9PC2p0SWMpUSM2NSxWzPyXTMLlbXmYa0R20xk
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